"Wha'choo talkin' 'bout, Willis?" was a catchphrase on which U.S. TV sitcom?

As Arnold Jackson, Gary Coleman popularized the catchphrase "Wha'choo talkin' 'bout, Willis?" in the show "Diff'rent Strokes" (1978–1986). When Arnold wanted to express disbelief or befuddlement (or the writers on the show just needed a laugh), Coleman would scrunch his face up and deliver his iconic catchphrase, "Wha'choo talkin' 'bout, Willis?" He was usually talking to his brother Willis played by Todd Bridges.

The comedy show focused on the fact that in 1978, two orphaned brothers (Arnold and Willis) from Harlem, NY were taken in by a wealthy millionaire. This event is at the heart of the TV series and is used to provide a plot basis of each episode.

"Diff'rent Strokes" is an American TV sitcom that aired on the NBC network and appeared on ABC from September 27, 1985 to March 7, 1986. The series was created by Jeff Harris and Bernie Kukoff. The principal writers of the series were Ben Starr, Budd Grossman, Howard Leeds, and Martin Cohan. Besides Coleman and Bridges, Conrad Bainand played Phillip Drummond, a widower, with a daughter named Kimberly (Dana Plato). Also, during the first season and first half of the second season, Charlotte Rae starred as Mrs. Edna Garrett, the Drummonds' first housekeeper.

The series became known for dramatically exploring serious issues such as racism, illegal drug use, alcoholism, hitchhiking, kidnapping, and child sexual abuse. Its executives were proud of the fact that the show produced 189 episodes during its 8 full seasons.