A pocket-sized cock tease, also referred to as a PSCT, refers to the younger counterpart of a relationship involving an older male and a younger female. The PSCT is very small, no more than 5' 3", and has the tendency to look like a rodent. Because they reside in your friend's pants, they believe that makes them your friend. They are wrong.
"Did you see the way Megan was sexing him up?"
"God, she's such a pocket-sized cock tease."