Rugrats/Tear Jerker

"I Remember Melville" is easily one of the most heartbreaking episodes in the series, featuring concepts of death being explained as Chuckie goes through the loss of his pet bug, Melville. On paper it sounds like a silly idea, but the execution of the episode is nothing less than impressive.
While the episode was intended as Nightmare Fuel, "The Mysterious Mr. Friend" is one of the most depressing episodes in the series. This toy clown named Mr. Friend merely wants to play with Tommy and his buddies, but creeps them out unintentionally, and he doesn't know better. The poor guy ends up killed in the end. Anyone see The Woobie?
This troper honestly teared up a little during the crying scene in the episode where Angelica thought she was going to move away. Sure, you know it won't happen, but I just love moments like this in shows where the Tsunderes that are normally the meanest people in the show soften up into a spongey puddle and show how much they care.
Chuckie's reaction to the dance at the beginning of the movie. It doesn't help how nostalgia-inducing and saddening the song is.
The Mother's Day episode, which explains what happens to Chuckie's biological mom: She died of an unexplained but terminal illness. It culminates with a letter the dying woman wrote to her son for him to read when he was older.
- It's natural to feel bad for Chuckie, but don't forget Chaz. He keeps her belongings stored away and doesn't talk about her much. It's clear that up to that point in the series he wasn't yet able to get over what happened to her. The scene where Chaz finds that Chuckie has gotten a hold of some of her stuff is downright heartbreaking.
The Flowers for Algernon Whole-Plot Reference episode where Chuckie gets an experimental treatment to get rid of his allergies only to have them come back.
The crowner of all of them, though, has to be the "All Growed Up" special, where it shows them as preteens. The whole special has a certain air of maturity and the pressures of growing up and experiencing new things. It then culminates at the concert scene, where Tommy and Angelica duet with some big popstar over a ballad that then flashes back to the series as a whole, showing scenes from multiple episodes. The creators did, indeed, write the special as an emotional look at the series...and this troper was definitely shedding some Manly Tears.
Acorn Nuts and Diapey Butts, the scene at the cemetery.
The movie's climatic scene involving monkeys, rain, and bananas.
While I did not shed tears, there is one scene that hit home for me as a kid. It's the plane trip in the second movie. It did not help that the first time I saw it, my mother had just died three months earlier.
- I want a mom that will last forever, I want a mom to love me whenever... I'm turning 18 in a couple months, and even though my mom is alive and well, I feel like crying when listening to that song.
Chuckie spending an entire episode trying to release his "sea monies" into the ocean, only to become heartbroken when he actually pulls it off. Knowing that they probably died ten minutes into the episode doesn't make it any less sad to hear him call out good-byes to them.
Anyone who grew up with this show and loves toys along with cute babies are bound to cry during The Curse Of Reptar's ending (All Grown Up). Basically It has a flashback at the time they were still babies and playing with Reptar. The end of the flashback has them sleeping under a tree with the Reptar doll with Tommy holding the doll and sucking his thumb. Cut flashbacks and have grown-up Tommy get a all rusted up Reptar, the same one I might add, and take it back inside to keep in his box. The final words really made this troper CRY! Not even Toy Story 3's incinerator scene can say that!
"Regarding Stuie" manages a pretty impressive Mood Whiplash, ending an episode-long string of Crowning Moments of Funny with a Tear Jerker climax. In a nutshell: Stu gets a head injury that briefly lets him communicate with the babies, but also screws up his memory and makes him act like a baby. "Stuie" then spends most of the episode wearing a diaper and palling around with Tommy and the gang. At first, Tommy is thrilled to have an adult-sized baby as a friend, but it all falls apart when he realizes that even the coolest baby can never replace his dad--and he seriously believes that he'll never have his dad back. The climax has Tommy silently weeping while looking at old pictures of himself playing with his dad, with "Stuie" (who still can't acknowledge the fact that he's Tommy's father) coming in to comfort him as he realizes how much Tommy misses his "daddy".