Moe "Mo' Guns" Jackson was Robert Freeman's wingman and friend from World War II. In their younger days, Robert caught Moe necking with a girl he liked and never forgave him.
He dies from an erectile dysfunction but Granddad does not know until a few days later due to Riley failing to deliver the message. At first, Granddad was all but overjoyed that Moe was finally dead, but refused to attend the funeral. However, the promise of something of Moe's being left to him in the last will was enough to coax him to Chicago.
On the plane, Granddad told a story to Huey and Riley of how he and Moe took down two German planes during the war: While flying, Moe and Robert run into German fighter pilots. Robert is focused on fighting while Moe is playing around. Moe decided to bet Robert (in the middle of the fight) two dollars that he saves him from being killed. After a brief argument, Robert accepts the bet. Robert manages to successfully shoot down one plane, but does not have as much luck with the second. Moe mocked Granddad when he shot at one of the Germans and missed horribly. Moe gets very cocky and closes his eyes while shooting at the Germans, but he himself misses horribly and shoots Robert. The German gets a clear shot insight, but is out of ammo. This forces him to retreat. When Moe opens his eyes he sees the German retreating, thinking that he was the cause, thus ending the fight. He then reminds Robert that he now owes him the bet money.
Moe wanted Granddad to deliver his eulogy because he thought that he was "good at saying deep things", but the eulogy he wrote to provide Robert with was just a list of lies to glorify Moe and humiliate his friend. After the funeral, it was revealed that the "something" that Moe willed to Granddad was a jar of nuts, Moe's last joke to his friend.
Moe was a loud, self-absorbed, immature person. Based on his personality, it came as no surprise when Moe asked to have his funeral on a party boat. Many people from his war days were at his funeral. They gave credit to him for Robert's accomplishments (Moe even somehow had one of Granddad's medals). According to Cookie Freeman, "everyone knew that Moe was an asshole".