A verb meaning to screw your friends over for your own personal gain.
Max certainly rosened his entire fantasy football league with that last trade.
I don't think you want to go on a trip with that guy. There's a strong chance you'll end up being rosened.
I never thought Scott would rosen me, but he told Becky that I have a girlfriend just so he could make her stop talking to me and go on a date with him instead.