Charlie horse is the worst common one, however I think I've had worse abdominal cramps during a bout of stomach flu, and also similarly when fighting a bad case of bronchitis my abdomen seized up from coughing...that was pretty bad.

Foot cramps are the worst! Especially when sound asleep when it hits! (I suffer from leg cramps in my calf muscles often, but I can live with those as they tend not to last.)

usually because I have a pinched nerve.

Ouch!

Somehow I had a neck cramp

Not a cramp
But a brain freeze during a DQ slushy