To make a complete mess of things. Derived from the traditional archery usage where, if the 'cock' feather was uppermost, the arrow would not fly straight.
When you're getting a slight boner in public, and you go into the bathroom and flip it north so it is held up by your pants. Usually is held up by tightening your belt.
(1) (Noun) The act of not fully inserting one's penis in an other's vagina or anus until about to cum and then just before one is going to cum, the full erection is thrust into the vagina or anus. (2) (Verb) To not fully insert one's penis in an other's vagina or anus until about to cum and then just before going to cum, the full erection is thrust into the vagina or anus.
The girlthought he was fully inside her while having sex until he gave her a cock up.