Naked Lad is a comic book character from the comic book of the same name, which is published in-universe of The Fairly OddParents.
The hero apparently looks just like Timmy Turner, only ridiculously more muscle bound, and disturbingly very naked. The superhero's cry is apparently a high pitched scream, because when Timmy does such a scream when he realizes he's nude in public, he draws the attention of two nerds who want his "naked autograph". As Timmy makes his way back home in the nude, many more people mistake him for Naked Lad, usually causing them to crash into something.
And apparently, he is supposed to be a parody of Timmy Turner without his clothes.