Mr. Gru's Old Fashioned Jelly was the brand name for a line of jellies produced by Felonius Gru and Dr. Nefario. The jellies are personally created in Gru's Lab by the Minions and Dr. Nefario. The product is no longer produced and has been retired.
Dr. Nefario's newest type of jelly under Mr. Gru's Old Fashioned Jelly is created from a combination of every known kind of fruit. However, due to its horrible taste, the jelly did not gain the approval of Gru, the Minions, or Dr. Nefario, who decided to leave to work for El Macho instead.
The line was shut down, but when Dr. Nefario returned to Gru's Lab, he used all the stock of Mr. Gru's Old Fashioned Jelly to combat the Evil Minions by mixing the jelly with the PX-41 Antidote and subsequently creating the Jelly Guns.