started in the 70's with a group of teenagers. Currently no ones claims to know its exact beginings; some claim it was a sound made by a former town employee when he cleared his throat, others claim it was an expression of disrepect towards authority : something that one could verbally say & get away with it.
Currently the trend is to have your picture taken while holding the HOOMPA bumper sticker ( black letters on a orange field ) in different places around the globe.
Screaming HOOMPA at someone was safer than swearing.
Using vulgar words would land you in BIG trouble, especially if you said it to a cop.