This person is known as Goofy. And he calls himself "Goofy" too.
Capricon 26 part 6: Friday (10-Feb-2006)
Someone and someone else in the background; Goofy giving a high five to a Viking in front of somebody else.
Capricon 26 part 21: Saturday (11-Feb-2006)
Bondo talking to Chris Dundon (with cane) and two others. Frank Rodriguez in yellowish-tan coat behind Chris, someone else, and Goofy in beard and hat (obscured) in background.
Capricon 26 part 22: Saturday (11-Feb-2006)
"Goofy" cooking up hot dogs.
Irvine SoCal Cosplay Spring Gathering at Mason Park part 2 (09-May-2009)