"Licking the beaters" means to lick and/or suck the testicles generously. The testicles can be sucked in a dry state or fluid such as semen and/or brownie batter may be involved. The term comes from the act of licking egg beaters after mixing up a batch of something tasty, like brownie batter and/or semen.
by JSmooth33 September 4, 2008