Typically, athletes cramp during competition. Rafael Nadal waited for the press conference after his win at the 2011 U.S. Open on Sunday.
If you can make it through that video without giggling uncontrollably, you are a far stronger person than I. Nadal is fine, and did his press conference standing, but him slipping off a chair and eventually laying on the floor while being attended to by a trainer certainly made for a memorable moment.