Had to go to the doctor's today...

Me and the wife went to the doctor's today to check up on my health.

After a couple of tests the The doctor said: "- I'm going to need a stool sample, a urine sample and a semen sample; so we can run a few tests."

I'm a little bit deaf and not hearing clearly, I asked my wife what he'd said.

Spoiler:

"Give him your underpants." said the wife