The context of the following conversation is Alex is a professional athlete.  He bet some strangers that he could win a race and won.:
Alex says Hey, those guys don't know me; maybe I can trick them for a bit..
The friend responds What are you going to do?.
Alex responds I look like an overweight, middle aged couch potato, but as a professional offensive lineman, I'm quick as a cat over a short distance..
The friend responds I've been listening to you guys brag about what great athletes you are.  Alright, my friend, show me what you can do..
Alex responds O.K guys, first one to that fence over there wins..
The friend responds Alright, Alex..