I know what you mean; that line seems to stick out a bit in context. If I can defend the stripper thing, though, stag dos are where the best man and other friends generally try to inflict all the cliches of stag dos on the stag as much as anything - he looked quite 'oh god, suppose I should grin and get through this' when then cake came in.

Perhaps early Rory had to be shown to be a bit not-quite in order to be more transformatively badass later on, too.