What is Buttonhole?
1.
To accost or detain a person in order to force them to engage you in conversation.
Man, I dropped by this party last night to say hey to a friend, and my ex was there, and before I could get out she totally buttonholed me in the foyer and starting crying about how we should get back together. It was messy.
2.
A vagina
Her skirt is so short and she wears no panties. You can almost see her buttonhole.
See