Rotten Jacoby Share definition Flag the act of jerking off in your friend's Red Sox cap and then putting it on his head when he is passed out. Tommy passed out too early last night and woke up with a rotten jacoby. Rotten Jacoby by Professor BJB June 11, 2009 0 0 Get merch Get the Rotten Jacoby mug. Buy Now — $32.95 See more merch