And you always cream in your jeans when your neck breaks. It has something to do with the pressure on the spinal cord being transmitted through the prostate.
(idiomatic,vulgar,by extension) To experience an orgasm while clothed; to be thoroughly excited or delighted.
1951, Donald R. Morris, China Station, Farrar, Straus, and Young, p. 52:
First time I was in here I come in with a Chinese M.P. We busted right in, that M.P. creamed in his jeans when he sees this colonel.