The actual Persian slang word with the meaning you quoted in urban dictionary "jendeh," also written "jende" in Roman characters, and you'll find these in the urban dictionary as well. So the bloke who wrote the entry for "gende" simply didn't know how to spell.
"jendeh/jende/gende," however you spell it, is of course stressed on the second syllable, like most words of Persian. You can hear it all over youtube.
Gende is actually a surname from Slovenia, thus having this misspelled in urban dictionary it is a slur on the family name. Please remove this duplicate entry, thanks.