peanut butter jar Share definition Flag A Peanut Butter Jar is the anus Firsrt I was fucking her pussy. That got loose and boring. Then I decided to stick it in her Peanut Butter Jar. End of story. peanut butter jar by Tommy R June 12, 2005 0 0 Get merch Get the peanut butter jar mug. Buy Now — $32.95 See more merch