A drink that brings a warm feeling down wizard's throats, popular in winter as a way of warming up.
Get's house elves drunk, but no intoxicating effect on wizzards.
Harry Potter: hey Ron, let's go to the three broomsticks and get some butterbeer!
Ron: Yeah but let's not bring malfoy, he's a prat.
Dobby: Harry Potter sir, winky's drunk!
Harry: Not more butterbeer is it?
Dobby: Afraid so Harry Potter, sir.