Smegma, dick cheese. More specifically, smegma that has been aged a few days or more under somewhat tight foreskin that doesn't usually retract.
Guy 1: This guy I met had a gorgeous dick but there was so much scottish cheese on it when I pulled his tight hood back, I couldn't. I'm talking like, crumbles falling off.
Guy 2: Where's this guy, I need me some scottish cheese now.