to hook up with somebody or have sex with them.
did you hear about sam and adam fooling behind the bleachers the other day??
Fooling is the art of performing sexual deeds > (greater than) a date/kiss/makeout but < (less than) performing sexual intercourse whether its vaginal or anal. The king of fooling is Fool-Her himself. Some think of Fool-Her as a god, a role-model or even a legend. There is a point system, and whenever you fool someone you gain (or lose) points depending on the physical appearance of the person.
*Matt starts fooling female by a BJ/footjob/reverse titty fuck etc*
justin: did you fool her yet?
matt: yes, i am the fool-her. end of question.