Nineteenth base is when you bite someone's balls off and stick it up your butt at exactly 10:17 am in a physics lecture at the front of the classroom while simultaneously touching the TA's areolae and solving a very very hard physics problem involving heat transfer of energy, kinematics and forces. All while drinking a extra large coffee - double double from mcdonalds that you got for free because you stole it because you're a naughty boy.
Wow, this morning I got to nineteenth base with my professor! Everyone loved it!