"Some Like It Hitman", "Duck Duck Party": The ending to the sketch reveals that Huey, Dewey and Louie's mother was an escort killed in a police shootout, with them asking their Uncle Donald when they can see her again.
Donald:(looking out the window on a stormy night) I don't know, boys. I just don't know.
"They Took My Thumbs", "The Train Man": The entire sketch is really heartbreaking, while also being absurd. A man gets stuck between the subway platform and the train. Unable to be safely extracted, he is forced to spend his entire life there and uses all of that time to focus on work. Only at the end of his life does he realize he should have spent that time with his family. He dies alone and the train finally bisects his now lifeless body, while the rest of society moves on.
"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 Ponda Baba, 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 becomes really sad for a split second when Jar Jar pulls off Vader's mask and is horrified to see that the little boy he once knew has the face of a burn victim.
"Ani-bo-bani! 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 boombox, 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 an ignorant garbage man who tossed him into the compactor of a garbage truck where he was crushed to death.
The worst part comes from what Joker says right before he dies:
Commissioner Gordon: Have you any last words? Joker: I know Jesus has forgiven me… Guard: Is that a joke? Joker: (sobbing)Nooo…
"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.
He-Man putting his father into a Bleak Abyss Retirement Home after the latter had been a jerkass roommate one time too many.
Nurse: (After decking King Randor) You'll observe lights out, or I'll knock your lights out. Take that in. Randor: (Beat, then cries softly for a few seconds)
"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. The fact that it's Frank Welker returning to voice Dr. Claw amps up the tragedy and the comedy.
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.
Santa going over his Naughty/Nice list turns out to be more work than he thought...
Santa: Alright, let's go over my Naughty and Nice list for this year. Green Elf: Well, Billy Marchetti in Rochester stole a candy bar... Santa: (confident) Looks like someone's on my naughty list! Green Elf: ...but he did it because his family's on welfare and his mom traded all the food stamps for heroin. Santa: (deflated) Oh. Um... Hm. That’s a tough one. (Cut to Santa peering in through a basement window, watching a kid curled up in a Troubled Fetal Position, shaking) ♫ He watches when you're home ♫ He knows when you're away ♫ He's also starting to realize ♫ That life is morally gray
The sketch for Dig Dug focuses on two miners named Bill and Harvey who get trapped underground with monsters from the titular game. Bill commits a Heroic Sacrifice to stop a Pooka while Harvey uses a bicycle pump to kill a Frygar before mourning the loss of Bill.
One sketch involves the Maytag repairman finally losing it due to staying at home all day because he never gets any calls for repairs. He argues with his wife which ends with him slapping her in the face. Then when he tries to apologize, she angrily leaves him to stay with her mother, and takes the kids with her. The repairman finally bursts into tears right before putting a shotgun in his mouth.
Maytag Repairman: Why don't they ever need service?! They never breakdown! But I do!
One sketch involves a couple kids playing a video game. One says he's thirsty, so the other shouts "Hey! Kool-Aid!" Nothing happens, and his friend even says that his imagination is a piss-poor answer to his thirst before going to the kitchen for a drink. That's not the tearjerker part, though. That would be the kid's response.
The Behind the Music episode of Dr. Teeth and the Electric Mayhem. As if Janice contracting Hepatitis and Zoot being arrested for a drug bust wasn't bad enough, poor Animal gets put down after he attacks Ed McMahon for insulting him. Making it much worse is how he's still fighting to stay alive as he's about to be euthanized and Janice sobbing in Floyd Pepper's arms as they helplessly watch. Even the ending is surprisingly sober: Dr. Teeth sincerely muses that good friends and good health are what's important, and Janice coughs weakly. Cut to credits.
The Bloopers host. Hoo boy, the Bloopers host. You know how every episode of his show ends with him committing suicide? Well, one sketch reveals why he's driven to do that: an abusive and alcoholic father who beat him as a child to drive his alleged gay away, the misfortune of getting a random girl pregnant in college during his first time, the resulting child, now thirteen, is pregnant herself and it's implied that the poor guy suffers from psychosis. Then we learn that his daughter ultimately miscarried.
A fake follow-up to Attack of the Clones shows Boba Fett utterly failing to move on from Jango Fett's death. The sketch begins with Boba playing catch with "Dad", but after he throws the ball, the camera pans to Jango's empty helmet and mitt lying on the ground.
In the third DC special, Batman complains how Superman can get whoever he loses back by going really fast and reversing time. Superman informs him that Batman can do it too but he has to believe. Cue Batman running as fast as he can, screaming "I'm coming mommy!". Superman was lying of course, just pranking Batman.
"Sonic Runs from Depression": There's nothing funny about this sketch at all. In fact, the implication is downright haunting, that Sonic has to run because mental illness is chasing him. The fact it ends with the actual phone number to the national suicide hotline, along with the 8-bit game music segueing into an ethereal instrumental music, makes it clear someone on staff lost someone to their battle and they don't want anyone else to take that way out.
Sonic: Gotta go fast, can't ask for help, leave my depression behind!
The Turbo Teen sketch is mainly Nightmare Fuel, with Brett incurring serious damage in car form which results in him turning back to human form with his arms, legs, and eyes gone, and presumably every bone in his body broken along with multiple organ failure, but it's downright pitiable to see him helplessly screaming and crying in pain and despair to the point that you're relieved when he gets promptly sandwiched between the car crushers.
": The ending to the sketch reveals that Huey, Dewey and Louie's mother was an escort killed in a police shootout, with them asking their Uncle Donald when they can see her again.Donald: (looking out the window on a stormy night) I don't know, boys. I just don't know.