look up any word, like cunt:
 
1.
1. To hug someone
2. When your arm rubs up against someone else's arm (on purpose or accidentally, doesn't matter)

Note: May also be called an "arm fuck" or "arm fucking".
Girl: Are they dating?

Boy: Just because they have arm sex on a regular basis doesn't mean they are!

Girl: Oh, just friends then?

Boy: Say... can we have arm sex?

Girl: Ew, no.
by Throwtheflowers March 25, 2014