when you pull out during anal sex and sign your name on their back with your poopy dick.
Don: You feel so good inside my ass....lets do this tomorrow...actually, lets get tatoos together.
Steve: I love you too, so for now I will just give you the john hancock.
Don: What is that?
Steve: Its when I sign your back.
Don: With what?
Steve: My dick.
Don: thats kinky. uh ah uh ah.....dont hurt me.