In early teenage years, for a group of developing boys to slide their penis from their slowly unzipped fly to show to the friend sitting next to them. They compare size and generally get rather hard. Then they test if they can ejaculate yet. For later dates they name these gatherings "a wankfest".
Billy: "Jeez Tommy yours is so darn big!"
Tommy: "Dude, I KNOW!!"
Jimmy: *Holds out a tissue* "GUYS GUYS... I'VE CAME!"
Billy: "We are SO having another wankfest next Friday!"