It's Always Sunny in Philadelphia Season 6 Episode 9
Dee Reynolds: Shaping America's Youth
Fresh off of last week's episode, Sweet Dee gets promoted to substitute teacher when her drama teacher gets injured from his fall. When she's unable to get the funding she wants to take her students to a broadway play, she decides to take the student to the bar for a screening.
Meanwhile, Dennis, Mac and Frank get into an argument whether black face on film is considered racist. They decide to test their theory on kids and offer up Othello with features blackface and Dee gladly accepts.
She arrives with the kids, the boys pull a last minute switch, and screen their Lethal Weapon 5. Charlie brings his mentee, Richie, a kid who dresses in ICP makeup. The kid shows up the next day in blackface and after the Principal watches LW5 on Youtube, he fires Dee and Charlie.