Sideshow Mel's son

Sideshow Mel's son is the illegitimate son of Sideshow Mel.

History
After Sideshow Mel spoke up during the student president debate at Springfield Elementary School, Bart asked him what he was doing at a school debate. Sideshow Mel then said that he was here as his illegitimate son went to Springfield Elementary. Sideshow Mel's son then said "oh, the shame."