Sometimes a muscle will threaten to cramp up again, for a few days after a major cramp, but I can usually avoid it by just backing off whatever I'm doing. Oddly, I frequently get cramps in my calves or feet during sex.
The weirdest cramp that I can remember was a couple of years ago. I got a call from my friends to meet them at a movie, while I was working out. Quickly hosed off and headed to town. Then in the middle of the movie, shoe-horned into those tiny little seats, I got massive pectoral cramps.
My friends thought I was having a heart attack.
I had to get up and stand in the back of the theater, so I could move my arms around.