Not literally meaning to hit something, but a form of comunication to talk to someone later. Also when your in a rush and you want to end a conversation with a friend for example you can say "aight ill hit me up"

1- A way to tell someone to induce in a violent action against you in a really hard way. For example punching someone very hard.
2- a way to tell someone to fuck you hard.

something someone says when they want you to call them on the phone.

When a woman wants a man to hit her in the face with his dick during sex

turning someone on in a sexual way to get them in the mood for sex

shorthand for "hit me up on the flipside" or "catch you on the flipside".