When a woman sticks her finger in her significant others ass and it potentially leads to other things going in there.
ex. Stacy kept trying to get that finger in there and i finally let her. Now i spend my free time shoving objects in my ass. That damn gateway finger is a bitch.

A pick me is a woman that is willing to do anything for male approval. She will embarrass or throw other women under the bus to achieve this goal. The unfortunate thing about a pick me is usually the men they are trying to seek approval from are of poor quality and treat women badly, leaving little real benefit for the pick me.