When you're a couple of pints in, there's almost nothing that's more fun than throwing sharp, pointed, face-endangering mini-arrows around, and for everyone around you to be totally cool with it.
When closing time rolls around, if you're in a nice country pub, they'll often have a lock-in: they close the doors to the public, serve you all night, and make you feel like a member of the damn family (which, for legal reasons, you briefly are). When an American bar closes, they play Semisonic.
There's No Dress Code
Bars often make you feel like you have to look like you made an effort. You can go to a pub in your dressing gown. That's not formal, even though it sounds like it. Ahhhh, Britishness.