the cacoon
when a two persons are spooning (naked) and the guy inserts his member into her rectum and leaves it there to continue spooning, untill it gets limp and it falls out( this would be the butterfly leaving the cacoon)
G and cole were spooning and G fell alseep, and cole got a raging boner, but as not to disturb the sleeping G he gave her a cacoon to avoid the awakening of G