Ass grabbery is the act of severe flirtation and/or lots of snuggling. A frequent moment when this phrase is required when a couple are being affectionate and staring into each others eyes. This is 'mental ass grabbery'. The actual ass grabbery comes later when they're flirting or snuggling. You may get the foreboding sense of impending ass grabbery is someone is coming onto you or if a friend is engaged in conversation with a nice young lady/man.
Friend: Look at that, total ass-grabbery.
Other Friend: Yeah, I ship them by the end of the night.
Someone: You have a girlfriend now?
Someone Else: Dude, did you not get the foreboding sense of impending ass grabbery?