Channeling the advertising skills of his most famous role, actor Jon Hamm appeared on a picket line this week with a “Mad Men” themed sign.

The sign, originally posted by comedian and actress Sarah Silverman, reads, “That’s what the money is for!” The line is from “The Suitcase,” an episode from the show that Mr. Hamm and his costar, Elizabeth Moss, call their favorite.

Mr. Hamm has joined the chorus of famous voices on the picket lines. Many others have come out with their own catchy signs based on films or TV shows they appeared in.

Mr. Hamm’s light-hearted viral sign comes as the Screen Actors Guild enters its fourth week of strikes. The union walked off the job July 14, joining striking writers.

The strikes have all but stopped entertainment production and lost the industry billions of dollars. The striking actors and writers are looking for improvements to residual payments as well as restrictions on how artificial intelligence is used in film and TV production.