A boyfriend who can only have sex once and then passes out shortly afterward. It could mean that he is too old, too drunk or he doesn't find you that attractive to have sex with you again.
Girl 1: Aww girl, me and my man did it ALL-NIGHT last night! He wouldn't stop. He went for five rounds!

Girl 2: You are so lucky! My man and I only did it once last night. He is a one round clown.
by cityguychicago February 17, 2010
Get the one round clown mug.