Buying beer and sharing with friends week after week is a good example of capitalism, as the bar owner is profiting so much from you and your friends buying all this beer.
Communism (of the Marxist variety) would be you and your friends being allocated the same amount of beer by the state, which owns the beer (along with all goods), and deals out the same amount of beer to everyone, regardless of what they do (i.e. what would have corresponded to their class).
I suppose there is another kind of communism where you and your friends live on a commune and some grow hops and some grow barley and some are in charge of fermentation vats and all just relax and drink their beer after a long day. That is, until the tax man cometh...