The Simpsons Episode 5.20 The Boy Who Knew Too Much

In a case ripped right out of the headlines, Bart is the only witness when Mayor Quimby's ne'er-do-well nephew, Freddy, allegedly assaults a snooty French butler. Hiding under a table in the kitchen of the Quimby Compound, Bart can plainly see that Freddy didn't harm a single hair on the butler's head. When the case goes to trial and Freddy is sure to be sized-up for a holding cell, the only thing preventing Bart from coming forward and clearing him is the fact that he'll have to admit that he was cutting school that day and receive a stiff detention sentence. As luck would have it, Homer is sitting on the Quimby trial jury and causes a delay of the proceedings because he enjoys being sequestered in a hotel. After Lisa's urging, Bart comes forward and clears Freddy. And as a reward for his honesty, Bart only has to serve four months in detention.