MAGICAL BACKGROUND : several hints
Spud mentioned that his great-grandfather used to be a magician, albeit apparently not a very good one.
During the talent show in which he does a magician act in honor of his relative, Spud unknowingly uses a magical incantation thought to have been lost for centuries to seal a Djinn away; it is, in fact, the catch-phrase his 'super gramps' taught him when he was younger.
The Gorgon sisters remark about how Spud is the splitting image of the warrior Perseus, who originally sealed them away. However, this might be entirely due to the Spartacus costume for the Fighting Trojans mascot he was wearing at the time, and does not necessarily mean he is related to the ancient hero.
Family tales of a mermaid city in the East River
Spud appears to have a relation with magic that may hint to a magical background. For example, he has displayed mastery with the use of two magical wands while battling Pandarus without any instructions or training beforehand, though he had trouble remembering what the spells would do.
Spud once maximized the smell of an onion, using a powerful voice, to defeat one of the giant bugs in the principal's room that Sigmund Brock sent.
He also gains magical frog-like powers in in one episode[15], although he goes back to being human with no magical abilities at all in the end.