And not just something you can find on any joke site, I'm talking rare, hilarious gems here 
one of my favorites I actually heard from Jamie Hyneman of Mythbusters, it goes like this:
A man goes into the doctor for a check up and asks "Alright doc, what's up?" the doctor with a concerned look tells the patient "Well I know this much, you're gonna have to stop masturbating." "WHY?!" The man replies. The doctor says "Because I'm trying to give you a physical for goodness sake!
one of my favorites I actually heard from Jamie Hyneman of Mythbusters, it goes like this:
A man goes into the doctor for a check up and asks "Alright doc, what's up?" the doctor with a concerned look tells the patient "Well I know this much, you're gonna have to stop masturbating." "WHY?!" The man replies. The doctor says "Because I'm trying to give you a physical for goodness sake!