Raptors

Brother 2: Aaaarh! (raptor noise)

Kyle: What the hell was that?

Brother 2: I don't have a penis. I have a raptor strapped to my waist. It gets upset when I suck in my stomach, it must be uncomfortable.

Kyle: I though your penis was made up of a bunch of worms.

Brother 2: Nah, that's Brother 1. They synchronize when he wants to have sex though.