Gorp was originally a shortened form of "Goronic Opossum",
and Goronic was originally a mix of Goron (that's the rock guys from Zelda) and Sonic the Hedgehog.
I used to just be Goron everywhere since like 2000-ish, but I was sick of always having to add a string of numbers to have a unique username, so that's why I threw Sonic in. :'D