There is no standardized test on earth designed to determine just how dumb these knuckleheads are. So you’ll just have to see for yourself. And in Season 5, the dumb just gets dumber as Eddy decides he’s had enough of the drudgery of school and hatches a plan to "bust out". Edd unwittingly becomes the school tough kid. And all three of them get lost in a series of flashbacks and find themselves unable to return "home". Yup, they are that dumb.