In the W.A.R. Journal episode Operation: Tiger Bomb, when Flippy experiences post traumatic stress disorder (PTSD), his name is spelled "Fliqpy" (the q symbolizing a flipped p to add to the concept of him "flipping"). This has become the nickname sometimes given to the evil/flipped-out side of Flippy by fans.
Flippy shares a lot of similarities to Freddy Fazbear from the Five Nights at Freddy's franchise: They're both bears, both have a good and evil side, they both kill people while in their evil state, they both wear hats, and both have gone through paranormal experiences (A Vicious Cycle). Their names are very similar too.
Good Flippy has the highest pitched voice out of the main adult characters.
Flippy usually repeats the same sounds when he flips out, starting with his normal self making a whimpering sound followed by a deep breathe and Fliqpy starts breathing evilly.
Party Animal, when he drank a smoothie containing the remains of Mime (although he wasn't flipped out at the time and probably didn't remember what he did while he was evil)..
Easy For You to Sleigh, when he killed Shifty with a Christmas cookie and took a bite out of the blood-covered cookie.
However, do note that Flippy's 'meals' are respectively a rabbit (Cuddles), a moose (Lumpy), a deer (Mime), and a raccoon (Shifty). Flippy being a bear shows it isn't quite as clear-cut as first thought.
Flippy is also the first character to resurrect in the second season.
He is the only main character (not counting Lammy and Mr. Pickels) who did not appear in Wrath of Con. A character in a Rorschach costume was seen in the episode, but the writers confirmed that it was a Generic Tree Friend.
Despite him being evil in almost every episode he appears in, Splendid has never tried to stop him.
He seems to be fairly wealthy since his house is full of trophies, statues, suits of armor, and a plasma TV, as seen in Easy For You to Sleigh.
Although he appears in a fairly low amount of episodes, he appears in allthreeepisodes of the thirteenth episode of the TV series.
Flippy is the only main character who has not yet been killed by Splendid (Debatable). In fact, they have never met face to face or even appeared in the same episode.
Counting him and Fliqpy separately, he is the only main character not to appear in Class Act excluding Lammy and Mr. Pickels.
On November 30th, 2009, Mondo Media posted a video on YouTube called All Hail Flippy showing (almost) all the episodes Flippy has starred in.
Flippy is usually considered the character with the biggest fanbase.
Contrary to some fans belief, it would appear that Flippy has not cured his Post-Traumatic Stress Disorder. In On My Mind, a Love Bite, he flipped out and killed Giggles. In Random Acts of Silence, where he flipped out and killed Nutty, Sniffles, and Mime. Therefore, his disorder is still active, despite him "getting rid of it" in Double Whammy.
In later episodes, an electric guitar riff and gunshot sounds can be heard in the background as Flippy flips out.
In Kringle Feast, Flippy was in a picture on the wall alongside Flaky and Lumpy.
The reason Flippy saw his alter-ego in Double Whammy might be because he overdosed on the pills he took earlier in the episode. It caused him to see an "evil counterpart" yet attack nothing but himself.
Flippy appears in a confessional on the June 2010 Wallpaper Calendar #1, which may indicate that he is a Roman Catholic.
In Hide and Seek, when he flips out, Flippy's green-yellow irises are only seen temporarily, after which they return to the normal Pac-Man shape for the rest of the episode. As this was his first appearance, it is likely that the writers hadn't come up with the idea of making them permanent until his next appearance, This Is Your Knife.
On the "First Blood" DVD, it says Flippy knits sweaters.
Of the characters that, so far, have appeared in the TV series, he is the only main character that didn't appear in any of the three segments of One Foot in the Grave, as he didn't appear until Lesser of Two Evils during Party Animal.
In Happy Trails Pt. 2: Jumping the Shark, Flippy has Pop's voice instead of his own. This is mainly because Pop was originally supposed to be in the episode, but since Pop isn't really the type of character to kill a character on purpose, and Cub wasn't going to be in the episode, he was replaced with Flippy.
So far, he has never killed The Mole, Cub, Handy and Russell individually - every time he killed them, he killed many other characters with them. In Flippin' Burgers, Cub (along with several Generic Tree Friends) was caught in an explosion caused by Flippy. In Remains to be Seen, he crashed his truck into a group of trick-or-treaters that included Handy, Russell and The Mole. Except for Handy (Happy Trials Pt. 2) and The Mole (Party Animal and Happy Trails Pt. 1), he has never met Pop, Cub, or Russell.
He is one of the few characters who haven't killed all of the four primary characters (Cuddles, Giggles, Toothy, Lumpy). The others are Petunia, Handy, Russell, Lammy, and Mr. Pickels.
He is the last character to die in the TV series and in Internet Season 3.
Flippy, like Splendid and Cro-Marmot, is usually not hurt by common things and rarely dies.
The only episode, to date, where Flippy has not killed anyone or flipped out is Without a Hitch (note that even though he did flip-out in Flaky's imagination, this is not counted as it did not actually happen). Flippy also killed Sniffles in Dream Job, however this took place in Sniffles' dream and the latter survived the episode, so this isn't counted either.
Flippy generally has a very difficult time killing Lumpy, having only caused the moose's death thrice ( the first of which was not shown onscreen, the second time was when possessing another object, and the third time with relative ease).
If one seperates Flippy and Fliqpy's as characters, Autopsy Turvy would be the only episode where he is the last character to die.
Flippy is similar to Lumpy in another way: both of them have cursed at least once in the series. Flippy said "Oh, crap! What the fuck?!" in Autopsy Turvy, and Lumpy said "What the hell?" in Hear Today, Gone Tomorrow, "Come on, dammit!" in Kringle Feast, and can at times be heard saying "What the fuck?".
Flippy's beret usually changes its position when he turns to the other side; much like Lumpy's antlers, Lammy's bow, Nutty's eye and candy, Russell's eyepatch and hook, The Mole's mole, Handy's tools, Sniffles' pocket protector, and Cub's diaper pin.
Pop and Fliqpy have a few similarities:
Both have the same voice actor.
They're both bears.
Despite being known for rarely dying, both characters die a lot more in recent episodes.
They frequently kill other tree friends (though Pop does not do it on purpose and has one common victim: Cub; while Fliqpy just kills everyone on purpose).
Both sides of Flippy are one of the few characters to eat/drink the remains of themselves or another character, the others are Cuddles (thrice), Giggles (four times, one time offscreen), Toothy, Lumpy (twice, one time offscreen), Petunia, Nutty (twice, one time offscreen), Pop (Offscreen), Cub, (twice, one time offscreen), Flaky (twice, one time offscreen), The Mole (Offscreen), and Russell (Offscreen).
Flippy is one of the main green characters. The other four are Nutty, Lifty, Shifty, and Cro-Marmot. His shirt also symbolizes the camouflage color worn by veterans during/after the war.