Well, I'm just saying coz it's so dark compared to his skin color! Yeah, that's fair enough esp if you compare it to Asians then it's pretty big. But I lived in UK so that size is just average to me lol. Ok bye.
Heard a dermatologist discussed it before. It's due to friction. Mas madalas ka mag masturbate, most likely it will get dark. It also happens to caucasians. Hindi nga lang nangingitim ung sa kanila. But you can tell na iba yung shade ng color ng dick nila to other body parts.
Meron din nagsabi na kung ano daw kulay ng utong, yun din daw kulay ng junjun nila. Hahaha. Except dun sa mga nagpatattoo ng nipples nila which is talamak sa ibang ibang asian countries nowadays.