Whether we are willing to admit it or not, most of us have an "image" that we want to project. This, in itself, is neither a good or a bad thing; it's only considered a problem if a preoccupation over said image leads to undue stress or unhealthy behaviors. As it's such a common human trait, it's only natural that most characters would likewise want to be perceived a certain way — be it a "cool kid," a "tough guy," or a "queen bee" — and would go to some lengths to protect that image.
But what if they have a beloved pastime that, if others were to find out about it, would threaten that image? What if being outed would greatly embarrass them, or their friends and family? What if they fear it would make them total pariahs amongst their social group? These characters have an Embarrassing Hobby.
The Embarrassing Hobby trope covers any example of a hobby that a character attempts to hide from others, because having others know about it would greatly embarrass them. It doesn't actually have to be shameful, dangerous, criminal, or perverted; it just has to be some level of embarrassing to the hobbyist. It can also apply to cases where the character actually takes pride in their hobby, but their family and friends are embarrassed for them.
While some Embarrassing Hobbies may be rather out there (like, say, collecting wads of bellybutton lint), most of them tend to be pretty ordinary pastimes that others make fun of for petty reasons. Stamp and coin collecting, while common hobbies, are widely considered "uncool" and boring. Building computers, while a useful (and potentially profitable!) skill, can get you branded a nerd. Some scorn fanfiction for being a foolish waste of time, in between long sessions of carefully filling out their "fantasy football" roster. So the embarrassment doesn't have to be justified by the nature of the hobby itself; it just has to clash with the image the character wishes to project.
While the Embarrassing Hobby trope knows no gender, there are a few differences in what kinds of hobbies each gender might find embarrassing. For example, a male may be embarrassed by hobbies they consider "feminine" even if they are traditionally unisex or even male-dominated (like cookery or the arts), while a female may be inclined to hide their passion for technical or scientific hobbies, if only to spare herself from snide comments. While some of these differences are becoming less pronounced over time, they do still exist.
Subtrope of Guilty Pleasure. Compare and contrast Closet Geek, which covers cases where a character may hide or avoid calling attention to their "nerdy" pursuits, but not necessarily out of shame. Contrast Real Men Wear Pink, which is specifically about male characters who enjoy so-called "feminine" hobbies, which they don't necessarily try to hide or feel embarrassed about.
May become a Shameful Source of Knowledge if the skills a character gained in the pursuit of their hobby are ever used or discussed. Can (and often does) lead to an Embarrassment Plot. See also Crime-Concealing Hobby, where the hobby itself isn't shameful but the motivation behind it is.
- Azumanga Daioh: One of Sakaki's defining character traits is her love for cute objects, which she collects. She's especially fond of plush dolls and has an even bigger soft spot for cats. But she hides it from her friends at school, because they have the wrong idea about her and she's too shy to tell them. So she'd be mortified if they ever found out. While there's never a big reveal moment, they eventually do figure out that side of her, and Chiyo even bonds with her over it.
- Cells at Work and Friends!: Taken to an extreme by Killer T, a leader of a squad of Killer T cells tasked with destroying the most dangerous viruses. He's taken his Jerkass Rated M for Manly image so far that he doesn't feel like he can openly do anything "unmanly" like...have friends, attend parties, play cell phone games, or watch sappy romantic comedies for fear that he would lose the respect of his squad and the populace. Most of the comedy stems from his attempts to enjoy his hobbies without outing himself.
- Genshiken: Ogiue's character arc involves starting out with a downright crippling sense of self-loathing over being an otaku and an amateur artist who's into yaoi manga. Over time and Character Development, however, she manages to move beyond (and put the reason she feels that way), and eventually becomes a competent club leader and a published manga artist.
- Wotakoi: Love is Hard for Otaku starts off with Narumi being dumped and ostracized at work for being an otaku. She changes jobs just to avoid the shame. She also states that not even she would date an otaku since they're "gross".
- In Zits, Pierce is secretly a scrapbooker and spends a lot of time desperately hiding the fact.
- High School Musical: One of the driving problems in the story is that multiple characters in the different cliques have their own secret, non-stereotypical hobby, like a skater dude being into cello playing. Troy's singing finally gives them the confidence to tell their friends... only for their friends to all collectively reject the notion that they can have those interests and tell them to "Stick to the Status Quo", justifying the embarrassment that made them hide their interests in the first place.
- Spaceballs: Sandurz catches Dark Helmet playing with dolls. (specifically, "Spaceballs: The Action Figures").
- Inverted in Discworld: Nobby is part of the Ankh-Morpork Folk Dance and Song Society and the historical re-enactment society, but doesn't find it embarrassing in the least, while his coworkers do.
- In Haruka Nogizakas Secret, the titular character is a rich, beautiful, musically gifted, athletic natural at almost everything... as well as a total anime and manga otaku. Her secrecy is less a matter of personal embarrassment, however, than the fact that her hobby being made public caused her to be bullied out of her former school.
- In the Lord Meren mystery novels, set in ancient Egypt, Meren's secret hobby is juggling beanbags. He does this because it's soothing, occupying his ever-busy mind when he's stressed out; however, as a highborn Egyptian nobleman, he has to conceal this habit because juggling is associated with low-born street entertainers and riff-raff.
- On 30 Rock, Jack had a cookie jar collection as his embarrassing hobby, which he gets rid of in order to get ahead at GE.
- In The Big Bang Theory, Sheldon Cooper goes to a cellar room in Caltech every day to play keepie-up with a beanbag. He tries to hide it from his friends and Hilarity Ensues when they try to find out what exactly Sheldon does in the half-hour he mysteriously takes every day.
- An episode of iCarly ran on the All Girls Want Bad Boys trope until the title character realized her "badboy" had a collection of girly toys. This was a big enough turn off for her to dump him.
- In Midsomer Murders, Troy secretly collected a comic called The Hawk which he was embarrassed about. Inspector Barnaby did not seem to mind when he found out, although he thought Troy was a bit stupid for keeping it secret.
- In an episode of NCIS, it's discovered that the Victim of the Week is a very prolific collector of vintage television lunchboxes. Though the victim is too... well... dead to be embarrassed by it at the time, he had been keeping his hobby secret from his neighbors and basically every member of the cast mocks him for it. Amusingly, due to the lack of any other leads at the time, they briefly investigate the possibility that he was murdered as a result of a lunchbox deal gone horribly wrong (he wasn't).
- In Ned's Declassified School Survival Guide, Jerry, one of the school bullies, was in the school's Sewing Club, which he would deny any time it was brought up.
- In the Psych episode "Not Even Close... Encounters", a childhood friend of Shawn's, who has grown up to be a rich, successful lawyer with a hot girlfriend, is revealed to have a secret room in his house where he keeps an extensive collection of comic book and sci-fi memorabilia and toys. He begs Shawn not to let his girlfriend know.
- On Seinfeld Jerry is secretly a fan of Melrose Place. His Girl of the Week is a cop and doesn't believe him when he says he never watches the show, so she has him hooked up to a Lie Detector and has the investigating detective ask him probing questions about plots going on on MP. Jerry is cool for a while but eventually cracks.
- On That '70s Show, everyone in the gang loves Styx. Eric is the only one who isn't ashamed of it.
- Mobster Vinnie Gognitti from the Max Payne series collects action figures, as Max finds out in the second game. This is especially embarrassing to Vinnie, as he strives to project a tough-guy image despite not actually being one.
- Deconstructed in Persona 4. One of the main characters, Kanji Tatsumi, loves knitting and sewing things. However, because he has the Face of a Thug, he's embarrassed about his hobbies because he fears it'll make himself seem unmanly. Even after going through some Character Development he's fairly embarrassed when discussing his love of "cute things".
- Arthur: Title character develops a secret obsession with Love Ducks, a fictional ultra-psychedelic children's show that may or may not be a parody (or Expy) of Teletubbies.
- Candace from Phineas and Ferb loves the children's show Ducky Momo, but being an average teenage girl, she can't let anybody find out lest she be teased to death.
- In The Replacements, Alpha Bitch Sierra is secretly a fan of a geeky sci-fi show but cannot admit it to anyone...at least, until the episode where she loses her spot on the cheerleading squad and is no longer obsessed with being 'cool'.
- In Scooby-Doo and the Alien Invaders, Buck, a mechanic whom the gang consider a suspect, turns out to have been sneaking around to gather wildflowers. He didn't want anyone to know he collected pressed flowers because it didn't fit his tough-guy image.