A halo reach around is where you give someone a reach around while choking them with a halo that way they orgasm super awesome,its like auto erotic asphyxiation minus the likelyhood of death.
The act of getting dissed for playing Halo Reach over doing any other things such as:
A) getting laid by your significant other
B) getting the hell out of the house C) being a productive member of society
Girl 1- "Why are you so bitchy today?"
Girl 2 - "I'm so pissed at him right now, I was dropping hints to him to come up and give me an Alaskan Pipeline, and he gave me a Halo Reacharound playing that damn game last night".