When you have sex with a girl from Philadelphia and you pull out to see another man's semen on your penis.
Man 1: dude! Did you smash that chick from the club last night?
Man 2: yeah, but that hoe gave me a Philly cheese dick. And it wasn't my semen.
When you have too much unprotected sex to the point that moldy cheese starts to grow on your penis, hence the name.
Example of Philly Dick Cheese:
“Yo Philip, I heard that you have Philly Dick Cheese, is that true?”
Love you cheese❤️
When you pull out of your hotel and some other dude's nut is on your penis.
I was rather upset when I pulled out of my girl and had a Philly Cheese Dick.