"Underwater basket-weaving" was a derogatory term for impractical university classes back in the 70s (?) and Mongolian is a stand-in for mongoloid, which fell

"Underwater basket-weaving" was a derogatory term for impractical university classes back in the 70s (?) and Mongolian is a stand-in for mongoloid, which fell off the euphemism treadmill as a descriptor for people with Downs syndrome. So "Mongolian basket-weaving forum" means "place for r*, useless people"