The Simpsons S13 E05 The Blunder Years

"Just a product of society that's lost its good manners."

After tricking Marge into thinking an advertising spokesman is coming to visit her, Homer takes Marge and the rest of the family to a restaurant. A hypnotist uses his powers on Homer, and makes him remember a horrific childhood incident where Homer found a dead body in a ravine. The Simpson family decides to investigate this and find out where the body came from.