Well, that's most likely because, like all gogo boys, Marcus is some varying degree of an exhibitionist. He's aware that if you catch him dancing at any of the clubs he frequents and after you've told him that you're a fan, that there's a 99.5% chance that you've seen the Playgirl photos and you've seen his rather ample endowment in all it's silhouetted glory.
He doesn't mind though and that's the thing. Marcus is a very BIG tease. (pun intended) Given his "gogo" attire which always leaves VERY little to the imagination, he knows where your eyes and/or hands will travel. He'll swing it in your face, even let you cop a cheap feel, only arms, thighs, and maybe cakes, but he won't let you touch the D though. Granted you'll be able to make out every ridge and vein in the underwear, given that it's fluffed a bit, but nothing else. Hell, that's how he makes money. It's all a part of the tease.