Buzz: To infinity...(muffled shouts which slowly die down)
Woody:(crying) And beyond.
The worst part is when he comforts Buzz.
Buzz: We gonna play tomorrow?
Woody:(smiles tearfully) You bet, pal! You bet!
"Malcolm X: Fully Loaded:" "The Last Pizza", where a girl sees her grandfather make his last pizza before the palace closes down, only to see it get dropped, run over, smeared and crapped on by hoboes. The grandfather died not long after.
"Drippy Pony": The ending to "NORAD vs. Santa", where after Santa is shot down, we cut to a shot of two children by their Christmas tree with no presents underneath. This shot plays under the credits before the girl starts crying near the end.
"Adultizzle Swizzle": The Star Wars sketch, where the alien who loses an arm to Obi Wan at Mos Eisley is shown to have lost his contracting job due to losing his "drawing arm".
"Endless Breadsticks": The sketch where a mercenary team murders a rowdy group of boys has the part where one of them sees his mom get her throat slit in front of him before he gets drawn-and-quartered. What's worse is that the mercenaries got the wrong house.
From the third Star Wars special, the sketch where Luke sees the difficulties of the Wampa whose arm he chopped off on Hoth.
"But Not in That Way": In the sketch parodying Punky Brewster, we see Glomer (from the Animated Adaptation) being ignored by a now-adolescent Punky, leaving him a starving and dying wreck, as well as being abused by Punky into enlarging her breasts.
Glomer gets the last laugh, though, when he enchants Punky's breasts to keep growing until they apparently smother her.
Glomer: Choke on it, bitch...
"El Skeletorio": The sketch where Woody Woodpecker gets a call from his dad saying that someone apparently close to him had been killed in a car accident. This reaction ("But I just saw her!") can really hit home for someone who lost a friend or family member in that fashion.
Most of the Star Wars sketch where Jar-Jar Binks annoys Darth Vader is just playing up the dissonance between the prequels and original trilogy for humorous effect, but it gets kinda really REALLY sad for a split second when Jar-Jar pulls off Vader's mask and is horrified to see that the little boy he knew has the face of a burn victim.
"Annie-Bo-Bannie, whasa happen to you!?"
The chicken's wife leaving him off-screen.
The sketch of Optimus Prime dying from prostate cancer. Then followed by Optimus talking to viewers that robots can't get prostate, but was shown as a demonstration on the importance of yearly prostate exam.
"The Sad Fate of Soundwave", when Soundwave hides incognito in a laboratory as a now outdated boom box, the oblivious scientists mock it and rip apart the cassette inside, in fact Rumble. Soundwave's reaction (helped by being voiced by original actor Frank Welker) just sounds so heartbreakingly pitiful.
Soundwave: Rumble! You're killing Rumble!
"A Grouchy Start" gives us the REAL reason Oscar's always so grouchy. When he was just a kid, he witnessed his cool older brother get killed by a ignorant garbage man who tossed him into the compactor of a garbage truck where he was crushed to death.
"The Munnery": The Clash of the Titans sketch shows the Kraken who was released from his cage, comes home to find everyone - including his family and work - has moved on without him and consequently hangs himself.
"Cyberdyne": Seeing Inspector Gadget helpless from the Skynet upgrade as his previous personality is overwritten with Dr. Claw's code, designed to terminate Penny and Brain. They crush him to death in the end à la The Terminator, which is equally horrifying and sad.
To say nothing of the minor sideplot where poor M.A.D. Cat is feeling ill and Dr. Claw learns the problem from the vet: he has feline leukemia. The Stinger even shows Dr. Claw holding a funeral, though it's played for laughs.
And in another sketch, Gadget is forced to kill again, as a US army drone, except this time he is fully sentient.
After making peace with the Mad Scientist in the Season 7 finale after teaming up to stop the Scientist's psychotic son... somehow the Robot Chicken ends up frozen in ice and revived...only to be put through the same torture he went through in the early seasons by one of the Mad Scientist's descendants.
The end of "Duck Duck Party" where the hooker duck turns out to be the mother of Huey, Louie, and Dewey, most pathetic is Donald Duck sadly lying to his nephews about their mother's whereabouts (his sister).