A name used for a person that makes you feel all emotions, like the girl being sung about in the song "Skeleton Key" by Margot & The Nuclear So and So's is being refered to.
"That boy is nothing but a skeleton key. He's not so special after all. He just opens up the doors to old emotions."
I need to take my girlfriend to the pharmacy to buy Advil because I skeleton keyed her... but first I need to wash my finger. While I'm there, I'd better buy lubricant for next time.
When a person is having sex with someone doggy style, and sticks their ring finger into the person being fucked's asshole, then turning their finger like a key