The action of going to the gym, not to workout as such, but to peacock around the weight lifting areas, standing in front of the mirror pulling poses, flexing here and there, walking around (like you are carrying a wheelbarrow) shaking your fellow gym buddy hand's, chatting, and attempting to pick-up the opposite sex. Usually attending the gym for many many hours at a time such egocisors are usually found congregating in groups of two or three, primarily locating themselves around the most popular equipment (or area with the most mirrors) during peak hour. Talking loud, slapping each other, making unnecessary grunting noise during the act of lifting weights (when they actually getting around to doing so).
John: Who's that super buff tanned bloke that just came and shook my hand like he was my long lost mate!?
Steve: Oh he's here every time I come! He's just doing his egocising warm up routine. Oh and look at that - his buddy who must have already done the rounds is over there right now tuning your girlfriend on the treadmill!