No line at the ladies'

Riddle: Where is the only place the mens' room has a long line and the ladies' room doesn't?

A metal concert.

On Wednesday we went to see Mastadon and Dethklok (from Metalocalypse). It was great. Mastadon was droney and serious, then Dethklok was silly and fun. They played all the greats... my favorites are Mermaider and Birthday Dethday with the lyrics, "R. S. V. P. please/To the death of theeee"

So silly.