How did Maniac pay for Russell and Piper’s school tuition?

Russell and Piper McNab grow up in chaos and squalor. With a drunk for a dad and a seemingly absent mother, they're pretty much left to their own devices. Unsurprisingly, the McNab kids lack the necessary discipline and sustained application for formal education. Maniac's own family background isn't a million miles away from the McNabs', but unlike Russell and Piper, he appreciates the value of an education. So he effectively bribes the two boys to get them to go to school.
First, he gives them pizza if they agree to go. But the McNab boys are cunning little critters and soon realize that they're in a position to negotiate a better deal. From pizza, they graduate to demanding that Maniac perform all kinds of crazy dares and heroic feats. He does so, hitting a telephone pole with a stone sixty-one times in a row; he takes off his shoes and socks and walks barefoot through the rat-infested dump at the foot of Rako Hill; he climbs over the zoo's fence and into the bison enclosure, where he proceeds to kiss a baby buffalo. In performing such bizarre (yet heroic) feats, Maniac is "paying" for Russell and Piper's tuition.