The act in which one friend thrusts their thumb, hitchhiker style, in a swooping motion toward the anus of another friend that is wearing pants, shorts, underwear, spandex etc. Once contact has been established, between the cracks, the one performing the act must shout "Gadhafi!"
*another acceptable method is placing the thumb onto the chair, couch, stool etc. in the linear path of the anus about to take a seat.
"Wow, you just Gadhafied me! That was a good one! getting me while I was tying my shoes!"
Gadhafi-ing is awesome! in public.