A guy I know at uni did the inviting two girls to the same movie at the same time thing by accident.
Of course—how else can I burst in and say “Hello dere!” like the Mad Russian at just the right comic moment?
So I take it this would be an inopportune time to ask you for directions to the Susquehanna Hat Company? 
(for the non-black-and-white-movie-set, this is a reference to a variation on the theme as performed by Abbott & Costello in In Society [1944])
The kid in the famous John/Joan case, who was born male and surgically altered to be female after a botched circumcision, started living as a boy again in high school - in the same town he’d always lived in. The cover story was that “Brenda” had moved away, and her cousing “David” had come to live with Brenda’s family. A family that included “Brenda’s” twin brother, Brian. Apparently, no one questioned it, for a while anyway.
I give up. What was so “special” about the cake? What happened to him?
I have a friend who, even in high school, looked 45. On a class trip once, a group of us broke off from the group and got in a bit of trouble for rowdiness at a minigolf place. When the owner of the establishment asked who was in charge of us, we introduced him to “The Principal, Mr. Windfall,” as played by my 16-going-on-45 year old friend, who swept us away to be reprimanded. Does that count?
I also had a very Perfect Strangers-like episode involving toilet repair, as recounted here: http://boards.straightdope.com/sdmb/showthread.php?t=134056
Bibliocat– the cake was laced with cannabinoids. It was one of several comestibles prepared for a party the night before. (He got through his presentation in spite of being somewhat less focused than he’d have liked to have been, and then he took a taxi home.) I guess if it were a true sitcom situation, he would have brought the entire cake to share.
Sitcom characters also like to lock themselves in closets, basement lockers, etc, especially at important times (parties, births). Has anyone ever actually locked themself in a closet?
Back when I worked in radio I had to break a DJ out of the men’s room. He had put on a “bathroom record” (i.e., a long song), run in there to do his business, and discovered he couldn’t unlock the door.
I didn’t pretend to be gay to live with my (then) boyfriend in college, but I did pretend to have a female roommate. She wanted to live with her boyfriend as well, so they pretended to be roommates, too, when in reality we switched rooms. Everyone knew, except my parents, and I have my doubts about them.
My three-year-old locked me out of the house once, when I went to take a bag of trash to the alley.
He evidently hadn’t watched enough sitcoms, though, because he didn’t use the opportunity to shave the dog or make prank calls to the chief of police. He just dithered around the kitchen for a few minutes, then unlocked the door again.
Oh, okay… head-smacking moment. Not at all what I was thinking. I was stuck on that “Don’t eat the cake in the urinal” kind of thing. 
My daughter locked herself in the bathroom when she was about 18 months old and couldn’t undo it. I was late for work because I had to take the doorknob off from the outside.
In college, a girl I knew did marry a guy to help him stay in the country. For some reason, his student visa was going to expire and not be renewed, so she offered to marry him so he could stay here for school. He was gay (think Carson on “Queer Eye” type of gay) and she was secretly in love with him, and thought marrying him would make him fall in love with her. All the makings of a happy marriage. Yeah, that one had sitcom written all over it …
When my sister was 8, she managed to lock herself into a hotel room and the rest of us out of it. She wanted to go to bed, but my mom and I were visiting with friends who had an adjoining room. Sis went into our room, locked the in-between door and went soundly to sleep. No amount of pounding on doors or windows would wake her up. One of the neighbors called the manager because of all the noise…and boy, was he mad…especially when he found out that we also had two dogs with us. :o
Another incident happened when I lived in Britain. My elderly, downstairs neighbors managed to lock themselves into their own bedroom. The bedroom door had a key lock and they were terrified of burglars, so they locked it from the inside every night. Somehow, the lock broke and they couldn’t get out. They caught my attention by yelling out the window, but they wouldn’t allow me to call the fire department or the police because they were too embarrassed. I passed them various tools through the window to no avail. Finally another of our neighbors happened by and was able to get them out by breaking in through the living room and removing their bedroom door.
So, closets, no…but other places, yep.
There’s a classic track on the Violent Femmes’ “Add It Up” – lifted from the studio answering machine. I think it was Gordon, and he had to admit that he’d be late because he’d locked himself inside his apartment and was waiting for his parents to come let him out.
A friend of mine got amnesia from a blow to the head.
We tried to cure him with a second blow, but he died.
When I was a teenager, my bedroom door was warped, so it wouldn’t close all the way. It’d get about halfway shut, and stick. One time, I got in a big fight with my parents, and I went into my room and slammed the door shut in a fit of pique. Then I went to open it to add just one more comment… and couldn’t get it open again. That was a pretty good sitcom moment. Went from “I hate you! I wish I’d never been born!” to “Can somebody please help me open my bedroom door?” in about five minutes flat.
But… it worked on the Flintstones!
Oh, and to give an answer for the OP, I’m pretty firmly atheist with Daoist philosophical tendencies, yet I dress up in black robes and perform the duties of a Christian minister on a weekly basis.
Why? The pay is fantastic, and I get to make people happy.
Actually, a guy I dated in high school suffered amnesia later. It was surreal.
About my brother being his own identical twin, I think he just went to the restroom, tousled his hair a bit, untucked his shirt, then came out as “Joe.” It used to be one of his favorite stories, but he doesn’t tell it since getting married. Maybe it emphasizes his lousy taste in women.
Sis-in-law is lovely, smart, and funny. If she ever finds this message, I meant his former taste in women. I swear!
I’m not always sure whethter it’s a drama or a sitcom, but there’s always plenty of interest where I live.
I live with fourteen other students in a cooperative house (we share food, mortgage and other living expenses. We make many decisions collectively.) We have a crazy neighbor and frankly we’re all a little crazy too (though possibly not as much as the neighbor). We also have a nemesis of sorts who wants to spoil all our fun like the principal in Ferris Bueller’s Day off (or any number of other movies) except he’s a local homeowner.
I can’t think of any examples that are classic sitcom fodder, but there’s plenty of crazy situations and colorful personalities.
Almost a sit-com moment … Back in the day when I was an aspiring screenwriter and had an agent, I used to go to the post office a lot, then this new guy starts working there. First time I dealt with him I smiled and said “hello”. Well as oft happened at the time I ended up going into the post office 4 times that week, and every time the available clerk was the newbie. He seemed to be convinced I was stalking him (I even heard him ‘whispering’ to a co-worker “jaysus she’s in here again, I’m not serving her this time”). Yeah right I really fancy you [at a cost of £40 worth of postage for 3 screenplays and 2 airmail to the US letters] :rolleyes:
Anyhoo I got so peed off at him and his assumptions that I was after his boney arse that I put a ring on my ‘wedding finger’ and wore it when I went to pay my parents electricity bill [which was in my dad’s name]. I made a point of drumming my [left hand] fingers on the counter as he dealt with the bill.
A few years later I was working in a video shop, he comes in to sign up for a membership, now this crowd are the membership nazi’s and demand that newbies have two forms of ID; one with a photo, and one with a current address (and they take your work phone number address too). He has none. I momentarily toyed with the idea of telling him I couldn’t let him sign up without those forms of ID as I had no idea who he was …