The new IT guy at my work goes to the bathroom at least 5 - 10 times a day. A couple of times, I was washing my hands and distinctly heard a lighter flicking from inside the stall. He coughs to try to hide the noise, and when he comes out, there's no smoke or odor. I thought he might be cooking heroin, but he was in there for only a minute or two.

WTF is this guy doing in there?

Singeing his ball hair for kicks.

Probably a diabetic, sterilizing the hypodermic needle. Diabetics also need to use the bathroom for the usual more usually than others.