What are the best “you don’t know who you’re messing with” scenes in movie history?

What are some of the great movie scenes where some punk messes with our protagonist but doesn’t realise they’re in over their heads until they get a beat down.The best examples of the kind of scene I’m talking about that come to mind are the bar fight from Jack Reacher (Tom cruise vs 4 guys) or the bar scene from Terminator 2 (I guess this scene often happens in a bar!) via /r/movies https://ift.tt/LSrNJ0s