[ Thank God for teaching Law. He falls back on his most scholarly voice at this point, keeping his grin from turning him into something truly hideous. ]

Yeah. More explicitly-- it involves men, self-pleasuring, usually in a group, often in contest with each other.

[ He chuckles now. ]

Her use is derogatory. Basically saying that everyone's just measuring each other's egos and that the pleasure they gain it ultimately pointless and fleeting. Which is accurate.