You are right about one thing, no one will piss 90 degrees. But the cup is plastic and absorbs heat and can lower the temp because what is room temperature? It isn't 98.6 degrees in most rooms is it. So to account for heat loss you get a temp range of 90-100 degrees. Go get a drug testing form. There is a box that says "Is the sample provided in the range of 90-100 degrees" and a little check box for it.

If you failed for 92 degrees then you aren't telling the whole story or someone made a mistake or someone just didn't like you.