Pitching a tent

From Frikipedia

Even with a kind lady lending a helping hand, this guy can't pitch a tent.

1) The process of putting together a tent.

2) A sudden infusion of blood in the male genital area.

Although the two definitions are very different, Frikipedia notes that both require concentration and a fair bit of fumbling in the dark, both get embarrassing if you can't do it right in front of an audience and both are completely inexcusable in a crowded lift.