The moment wasn't even over before my brain started screaming inwardly, "Oh crap. Oh crap crap crap crap CRAP."
Next day at school, guess what everybody started singing as soon as they saw me. I went the entire day hearing that damnable song every time I turned around. And since Cheers was popular, the song remained in consciousness for a while...and it still has. To this very day -- and it's gotta be 25 years since that episode ran -- I will still occasionally find someone whose memory will be jogged, and they'll get this very specific gleam in their eye, and they'll ask, "Hey, were you ever a fan of the show Cheers?"
To which I will sigh, and say, "Yes, I loved the show, and if you sing it I will break your arm."
This threat is never taken seriously.
And that is the day a sitcom ruined my life.
(Via Ken Levine, who is, at the very least, an accomplice in this crime.)