My doctor told me to ejaculate in a jar and bring it in the next day...

So I come back the next day with an empty jar. "What happened?" The doctor asked.

"Well," I reply. "I tried with my right hand, then my left hand, but it didn't work. So my wife tried with her left hand, then her right hand, then her mouth, but it didn't work. So then my neighbor tried with her right hand, then her left hand, then in between her legs, but it STILL didn't work!"

"You asked your neighbor?!?" The doctor exclaimed.

"Yea, I couldn't get the jar open."