The back and forth movement of an erectile penis moving back and forth "in and out" of a girl's vagina; it usually is a repeated movement when it comes to sex and pleasure for the lady.
a termed generally used by escort services in their ads. Meaning: the escort is able to go "out" to your home or hotel, or she offers her services "in" her home or hotel room she has for the time her services are offered.
When one person is in the for the other, the other person is out for the other, and they end up hooking. There are other combos in the matrix (in in hook, in in no hook, in out no hook, out out hook, out out no hook).
Tyler: "Did y'all hook"?
Ryan: "Yeah... it was an in out hook. She was in, I was out, but I was so ravenous, so I justwent with it anyway."
We went down to the derelict casino where we came across Billyboy and his four droogs (friends); they were getting ready to perform a bit of the old in-out-in-out on a weepy young devotchka (girl) they had there - from the 1971 film "A Clockwork Orange"