Bob Ball sends this in: “Don’t those small bubbles rising from near the stern mean that whoever’s behind the wheel is drunk?”

The bubbles seem like a odd addition to an otherwise clever double pun. There’s the obvious pun around the sailors being on the mast, and the alternative definition of mast: “fruits, seeds, or nuts (such as berries, pine seeds, or acorns) of trees or shrubs that serve as food for wild or domestic animals and typically accumulate on the ground”