After the magnets comment Shaggy says “and I don’t want to talk to a scientist, yall mother fuckers lyin, and gettin me pissed.” This is obviously an expression of frustration with his inability to understand basic scientific concepts. You can see the pain expressed in Shaggy’s face as he recalls how science class made his brain hurt. While he wants to know how magnets work, he is not willing to accept a scientific explanation.