For my 40th b-day, I went to Disneyland with a few good friends. We had great fun. Willow and I sang the "small world" song over and over and drove everyone else mad.
Of course, I lived in LA at the time, so it wasn't that far away.
If he's into Star Trek, maybe you could dress up like a Klingon female and perform the Klingon mating ritual.