Top definition
A day on witch your strong sperm isn't being produced. All of the good stuffs been jerked away and now you're only left with bottom of the barrel seed. Children born on this day are twice as prone to developing mental retardation, lack of athletic ability, and/or ugliness.
"I got her pregnant on a bad sperm day, so he's practically not even my kid."
by 6J6W6 June 11, 2011
Mug icon

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug