Originally Posted by AntiDrama

Ahh... this could be one of the causes:

Often, I find myself wearing 1 shirt throughout the day with no tee-shirt underneath. I then visit my girlfriend, we end up having sex, etc... and then when the day ends - I go back home and sometimes sleep in the shirt I wore for the day (because I still do not have a tee-shirt on underneath it... so I figure, okay sleep in it - then in the morning throw it in the dirty clothes hamper.

Anyway, I guess sweating from sex... and then the wetness is absorbed by the shirt and then dries... and then I wear it. That can't be good for the skin.