It describes any guy who from the back looks like they could be hot, but you're not sure, as haven't seen their face yet.
"Damn, you should see him from the front - totally hot! A complete JOSEPH!"
Passenger: I can't man I got Guccied last week.
man 2: Look at that Negro! Shes eating pizza
james: That, my friends is no black guy or indian. That, is a Ralph.