According to redditer TyPiper93, Bart was a Stonecutter and was even a member of the organisation before Homer.
The Simpsons episode 115 introduces us to Springfield’s chapter of the Stonecutters, a secret organisation based loosely on the Freemasons. We discover that to become a member of the Stonecutters you must either be the son of Stonecutter or save the life of a Stonecutter.
Now, consider 2nd season’s episode Blood Fued in which Bart donates blood to save Mr Burns’ life. Because Mr Burns is a member of the Stonecutters, Bart therefore becomes eligible to join the Stonecutters. As the theory goes, this is when Bart joined the secret organisation, long before Homer did in season 6’s Stonecutter episode 115.
Why would Bart want to be a member of the Stonecutters? Well, their organisation values greed, power and privilege … an enticing group for a mischievous young hoodlum like Bart.
One piece of evidence to suggest that Bart is a Stonecutter comes at the dinner table when Homer discusses with his family the observations he made at work regarding Lenny and Carl’s special treatment. Homer posits to his family that he feels there must be some sort of conspiracy going on. Bart quickly replies “A conspiracy, eh? Do you think they might be involved in the Kennedy Assassination in some way?” When Bart says the word “conspiracy” he gives Homer a wink, possibly trying to throw Homer off the trail of discovering the Stonecutters’ secret society.
Later in the Simpsons’ house, Grandpa Abe claims that he is a Stonecutter, but Homer, Marge and Lisa completely ignore what anything he says … until Bart tells everyone at the table that maybe they should listen to Grandpa. But why would Bart change his mind about Homer joining the Stonecutters? Maybe he received orders from number 1 to help Homer become a Stonecutter since he has already found out about the organisation when he spied on, and disturbed, one of their meetings.
Additionally, after we find out that Homer is the Chosen One, there’s a scene where he’s sitting at home having a philosophical debate with Lisa about divine power and, when he realises he’s about to lose, he ends the debate by demanding “Take the girl away!” Bart then immediately comes out of nowhere, grabs Lisa and takes her away; Bart even gives Homer a bow after taking her away.
Another piece of evidence to support this theory is the strange way that Bart seems to avoid punishment from Principal Skinner at school. Amongst his misdemeanours, Bart has caused structural damage to the school, caused the teachers to strike and committed multiple counts of vandalism but he somehow manages to avoid severe punishment by Skinner who, of course, is also a Stonecutter. Perhaps Skinner tries to pull strings to limit the punishments that Bart receives.
You may be asking “If he was a Stonecutter, then why wasn’t Bart at the meetings?” Well, Homer was given the number 908 when he was initiated and during the dinner song scene, there are barely a hundred people at the table … so it’s probably not a requirement for a member to be at every meeting. Alternatively, considering Moe mentions to Homer that there are hundreds of Stonecutter chapters all over the world, Bart may be part of another chapter.
To conclude, there is strong evidence to support the theory that Bart is a Stonecutter and was even one before Homer.