The end of "Autopsy Turvy (AKA Double Whammy Part 2)". After revealing the epic battle between the Flippys and Fliqpys is really just Flippy fighting with himself the entire time, both sides, badly battered, pull out at least a dozen copies of themselves each... and then they go all out against each other. The entire second half of that episode counts, too. Turns out that Flippy is every bit as badass as Fliqpy.
Fliqpy fighting Tiger General in "Operation: Tiger Bomb". The General is the only character in the entire franchise (Other than Lumpy) to put up a tough fight against Fliqpy, and actually came pretty close to killing him. It's one of the very rare instances where the show would actually want you to root for Fliqpy.
Flippy also gets a point for this: He just witnessed both his best friends get brutally murdered, blown up and shot up, at Which Flippy has to hide in the corpse of one of his friends, only to quickly get found out. How does it play out? He turns into Fliqpy (for the first time canonically) and just obliterates everything Tiger-related, fights the General (who also cut off his hands), and wins.
Even the General himself counts, as a determined character who just won't give up, and seems to be almost unbeatable, even after Flippy flips out.
Lumpy fighting the demon-possessed Cub in "Read 'em and Weep".
Flaky gathering all her courage and stabbing Flippy in the eye, trying to kill him on purpose, in "Without a Hitch". Though, since she did it to the innocent and helpful version of Flippy, this earns her a Karmic Death via airbag.
In "By the Seat of Your Pants", Lumpy manages to outsmart Fliqpy. To make things even better, he does it while panicking. (As pictured above) Lumpy managed to kick Zombie!Flippy's ass earlier in the Halloween special "Remains to Be Seen". After his hand gets bitten off, Lumpy attempts to replace it with a chainsaw, but gets a leaf blower instead. Nevertheless, he manages to inflate Flippy's brain and draw in the other zombies, killing them in the ensuing explosion when Zombie!Toothy pops the brain while trying to eat it.
In general, it's awesome to see Fliqpy get killed for a change.
In "Doggone It", Lumpy faces off with a giant squid with only a mousetrap and wins.
In the same episode, Pop finds Whistle attacking Cub, and immediately begins to attack the dog, even letting it bite him while he calls Lumpy the animal controller. Though we don’t see Cub for the rest of the episode, it’s possible that Cub actually survived. It's just impressive to see Pop actually save Cub.
Lifty & Shifty having the upper hand on Splendid in "Gems the Breaks". Special points given here because they're the only two characters that give Splendid a hard time (besides Splendont, that is). Also, extra points to this episode for breaking Splendid's immunity, and having him actually die (though the explosion in "Class Act" killed Splendid as well).
In "Wrath of Con", when Splendid lifts up the chunk of the building, the second time this is shown, it Art Shifts to a painted style. Not only that, he is given pectoral muscles and an Exposed Animal Bellybutton. Unlike other Art Shifts, this one is still.
In "Easy For You to Sleigh", Lifty & Shifty go around on Christmas stealing from people and inadvertently killing Pop and Cub by blocking the chimney with their tree (though Pop didn't help matters by disabling the smoke detector). Then they rob Flippy, and wake him up after having tied him up. He proceeds to flip out and kill both of them, dissecting Shifty with a christmas cookie.
The "Still Alive!" trailer. After 2 years of waiting Mondo has finally decided to release new episodes again.
In "Spare Tire", Giggles was bisected and she died. But at the end of said episode, Sniffles was able to fix her torso using a tire, and somehow, this brought her back to life.
Lumpy using nothing but a pogo stick to stop Lifty and Shifty from stealing his elephant and the rest of the Tree Friends' pets in "Junk in the Trunk".
In general, while Lumpy tends to be Lethally Stupid, he is continously shown to be an Action Survivor. Managing to survive and endure several situations that anyone other than him would've been quickly killed in, such as in "Snow Place to Go", where he's the only one of the group to find civilization. Even with his stupidity, Lumpy has occasionally displayed high intelligence compared to the other characters. For example, in "Doggone It", he's the only one who realizes what causes Whistle the puppy to attack.
In "Who's to Flame", the whole town is caught up in a blaze, the critters are maimed by the usual freak accidents, and it ends with the whole town going up in a mushroom cloud thanks to The Mole lighting a match near a leaky gas pipe. So where does the Awesome cut in? At the very end, we see Mime riding his unicycle and holding the cat Cuddles was attempting to save earlier and, despite a Screw This, I'm Outta Here reaction, he and Mittens walk down a set of invisible steps and the episode ends. Let me repeat that. MIME, one of the characters with a big death ratio, was the ONLY one confirmed to have SURVIVED the blast by sheer luck. Made even MORE awesome by the fact that he tried to "tell" the others about the fire starting and no one believed him. Lumpy may not be the only Action Survivor after all!
This wasn't Mime's only Action Survivor moment. In Mime to Five, he's the Sole Survivor after Lumpy's man-eating ducks go on a rampage, and Word of God says that he managed to survive the events of Concrete Solution (albeit offscreen).
In general, it's always satisfying when a character who usually has a high death ratio survives an episode where they have a starring or featuring role, particularly when most, if not all other characters in the episode have died.
Pretty much anytime Handy builds something offscreen, despite his lack of hands. Not bad for a beaver with amputated arms.
A minor one but in From Hero to Eternity, Sniffles and Nutty are in a tree house and it's implied that Nutty is winning. Let me repeat that for emphasis: Ditzy resident Cloudcuckoolander, Screwball SquirrelNutty.
In Keeping It Reel, he also is insensitive, as the only thing he does after someone's eye is in the camera and burns is to merely boo the movie... right before it's implied he is Fliqpy's next victim.
