An exciting, secretive hand-job performed on a fun bus on the ride back from your trip. The thrill of the trip combined with the hand-job itself creates an explosion in your pants. If done right, none of your seat neighbors will be disrupted.
Not to confuse with "funny business", Fun Business includes acts, which are considered abnormal, unusual and fun. It does not have to be a bad thing, it's just something, you wouldn't normally do, a crazy action, for example getting a tattoo while being drunk, hooking up with 4 different people a night, swinging on a chandelier, etc.
"Yesterday has been classic Fun Business."
"Oh I know, you just went on stage and started singing in front of alle these people!"
Kiljoy, stick in the mud; everyone is having FUN FUN FUN, and this person acts as though he or she is not having FUN ...a real terd ...and Fuck 'em, feed 'em fishheads type person "a FUNBUSTER!!!"