Pre employments are unobserved so you will be able to do it with very little pressure. Practice a couple of times, to get a feel for how long your body holds temperature. If your piss is clean and temp is in range mid to high 90's your good to go. scroll down a little and you'l see a tutorial that I made about making a cheap beeperless digital thermometer to help in just this kind of situation.
STIMPY21