"Routine", Ulrich takes a naked Angst Shower when he wonders if Yumi loves him.
"Fight to the Finish" Aelita takes one, worrying about the dream she just had.
Parodied in The Simpsons episode "Guess Who's Coming to Criticize Dinner", with Homer sitting in a tub, looking traumatized with wide eyes as he crazily scrubs at his skin repeating, "Still not clean, stink of failure still on me! Still not clean, Stillnotclean!" after the newspaper editor rejected his first draft of his food review.
Not exactly a shower, but in "Black Widower", Sideshow Bob splashed water from the sink all over his body after making love to Selma.
In the Drawn Together episode "Requiem for a Reality Show", after Captain Hero degrades himself sexually to Foxxy Love in exchange for food, we see him sitting in the Shower of Angst eating cookies.
Parodied in a Family Guy cutaway, where Darth Vader showers in a depressed manner after a hard day at his job as a meter maid, and just before he resolves to apply for a loan to build the Death Star. On the commentary, Seth MacFarlane refers to the trope, saying every pretentious independent film needs to have an obligatory scene where the character "showers the pain away". (this is especially funny due to Vader wearing his helmet both in the shower and all the other scenes).
Parodied again when Peter the Strawberry took one after being "violated" by a worm.
"He was my neighbor...and he violated me! Now I'll never know the inside of a fancy pie!"
Stewie sits fully clothed under the shower spray crying as he washes Rupert after learning that New Brian humped Rupert.
Murderface does this in an episode of Metalocalypse after a gay doctor accidentally (or not) jerks Murderface off in his face and he goes into a state of paranoia about his own sexuality. Later mirrored in a still-shower-based Redemption in the Rain moment when Murderface finds out that it was the doctor, not him, who was gay.
In the Spongebob Square Pants episode "Squid's Day Off", Squidward goes crazy from paranoia after leaving Spongebob at the Krusty Krab by himself and tries to take a bubble bath to calm himself down. He ends up hallucinating while in the bath and seeing Spongebob everywhere.
King of the Hill has Dale crying naked and fetal-positioned in the shower in the episode "The Trouble With Gribbles" on realizing his plan to get Nancy a facelift is resulting in her breaking up with him.
In The Ren & Stimpy Show Ren who is exhausted from work, and Stimpy's nonsense, takes a bath in very dirty water, while wearing lipstick.
In the Regular Show episode "Muscle Woman", Muscle Man, who is distraught after breaking up with his girlfriend, spends a lot of time crying in the shower. It's total Fan Disservice.
South Park: One of the scenes opening "Ass Burgers" which show Stan with a disaffected, sad face have him standing in the shower, standing still just like this.
In the Disney short Feast, we see Winston's owner taking one after his girlfriend breaks up with him.
Harvey Birdman, Attorney at Law does this in an episode where he discovers that the accused terrorist he'd gotten acquitted (The Unabooboo AKA Boo-Boo from Yogi Bear) was guilty after all. After Harvey slept with him. Or something. It's a very surreal episode.
Coach Stopframe takes one of these in Moral Orel because he's become obsessed with Clay and Clay is still repressing his bisexuality.