His girlfriend had been fending off the 5 drunk guys for most of the evening by explaining that even if she was going to ditch her boyfriend, she can't possibly leave without finishing her beer, which she is keeping perpetually full via careful sleight of hand where she's just pouring it back and forth into and out of the pitcher.
However the drunk guys are also drinking, and eventually she can't afford to buy another pitcher for the table so she can't keep up the ever-full beer glass trick. At this point she has to resort to setting up the pool trick shot that she's never seen anyone but her boyfriend pull off, and says she'll leave with whoever manages the shot first.
That buys her another hour or so and then, finally, her boyfriend makes it back. He looks like shit, hair down and just a mess, he's wearing an entirely different jacket that he got from an alley, and barely recognizable—especially to 5 guys who've been drunk for hours now. He lurks for a minute, finds out what's going on, and proceeds to pull off the trick shot first try. Throws the jacket off, fixes his hair with a hair tie his girlfriend lends him, finally looks like himself again, and THEN beats the shit out of them with the pool cue.