Keeping California’s waterways clean isn’t a laughing matter, but a new campaign urging people to stop using them as a bathroom is.

Glass/McClure in Sacramento has created an animated print cam paign for the California Department of Boating and Waterways that urges boaters not to dump human waste into the water.

Running now through the end of summer, ads feature the line: “Don’t be a party pooper. Dump at the pump.”

One shows a character called the “Dump Donkey” dumping waste from a boat dubbed the S.S. Sloppy. Text calls him “a lazy boater who doesn’t use pumpout stations” and a “jackass” who “ruins everyone’s day on the water.”

Similarly, the “Gutless Guppy” on the S.S. Stinker is referred to as “a cowardly boater who dumps when no one’s looking.”

Glass/McClure art director Brantley Payne admitted human waste was not something focus-group members were keen to discuss. “No one wanted to talk about it because it’s so taboo,” Payne said. “So humor was the best vehicle.”