When you thrust your hips up and down while your legs are spread over and over (very fast), causing your dick to slap up and down, off of both your stomach and from between your legs.
Jess opened the door to my Cock Dance in the mirror. Needless to say, she was impressed.
a cockmance is the gayest level of non-gayness possible, without actually being homosexual for a straight man. It is the next step after a bromance.
"yo man, you and your friend say a lot of pretty gay sounding shit to each other every now and then, whats up with that?"
response- "nah its cool, we're not gay. we just got a mean cockmance goin on"