All the times (that I know of) Eminem has mentioned penises in his songs:
1. Role Model- "Don't you wanna grow up to be just like me?/ I tie a rope around my penis and jump from a tree."
2. As The World Turns- "Just trying to buy me some time, then I remembered this magic trick/ Den den den den den den, go go gadget dick!/ Whipped that shit out, and ain't no doubt about it/ It hit the ground, caused an earthquake and power outage."
3. Criminal- "So as I got older and I got a lot taller/
My dick shrunk smaller but my balls got larger."
4. What's The Difference?- "So what's the difference between us? We can start at the penis, or we can scream 'I just don't give a fuck!' and see who means it."
5. Bitch Please II- "Aww naw, Big Slim Dogg/ Eighty pound balls, dick six inch long."
6. Big Weenie- "There's no denying, that my weenie is much bigger than yours is/ Mine is like sticking a banana between two oranges."
7. Berzerk (*not really but kinda)- "The art of MCing mixed with Da Vinci and MC Ren/ And I don't mean Stimpy's friend/ Been Public Enemy since back when you thought PE was gym."
So there it is. All the references I can think of. I have no idea if he practices pe but the guy clearly has dick on the brain. But then again, don't we all?