Basically it means to beat someone down really bad with punches, kicks, elbows, and so forth.....there doesnt' really have to be a whole lot of blood (though the more the merrier).....but as long as the dude's hobbling off and wakes up the next day with a good reminder of why its a bad idea to fuck with you in the first place. Thats what it would mean to "beat the fuck out of someone"