guitar face: the face you make when in pain, ecstasy or passing massive amounts of gas. (bonus link HERE - am I the only one that laughs?
safety buzz: The amount of alcohol (or other substance) intake neccessary to provide a reason to try and make a move on someone. If this person is not receptive to the advance, then he/she can later claim that it was the substance talking and not them. However, if he/she welcomes the advance, there is nothing to worry about.
break the seal: The point at which you first piss after you have been drinking your favorite alcoholic beverage and at this point you will be pissing every ten minutes.
unprotected sleep: turning off your alarm clock and immediately going back to sleep; risking not waking up for a job, class, or other daily task.
Urbandictionary.com: usually crude; always entertaining.