"The Curve" is an alternative method of asexual reproduction, consisting of a hermaphroditic individual inserting his/her penis into his/her own vagina. It's called "The Curve", because of the distinctive shape the penis makes as it's inserted. "The Curve" refers to the act; it can be expressed as a verb with "Curving".
(Verb) "Well Billie, I have both the gun, and the holster, so I'll let you choose. What do you want to do?" "Honestly Sam, I'm content just sitting here and watching you curve yourself."
(Noun) "Wow, she's hot." "If you say so, but it looks to me like she's got The Curve going on."