There's no "flashing" here, but there's plenty of lecherous as a dirty man trolls around London filming whatever catches his attention — which is usually butts and boobs. He might think it's harmless fun, until he learns otherwise the hard way and gets knocked out (which mayb have possibly been his goal all along).
The parental advisory is no joke. This is pretty messed up. We're talking exclating acts of hijinks and violence. Drinks, debauchery, knives, throats and blood. We're talking erotically-charged jailbait death frenzy. And don't confuse the end for a purifying baptism. It's the exact opposite.