Thanks to all of you for your contributions.
So, the general consus is : Il bibitaro (m.) and la bibitara (f.), right!?
N.B. You'll find concessions workers selling concessions to spectators at various events (sports events, recreation parks, Disney themes parks and whatever-theme-parks that are out there, etc.)
Isn't it "omino" derogative?
But, I also heard of "L' omino verde" which is funny