If a puddle of liquid is present in the same tile as a shower, any duplicant passing that area will become stuck in an almost endless cycle of stepping into the puddle, jumping into the shower, only to immediately step into the puddle again and shower ad nauseum. It does seem some errands like getting food override this loop and breaks them free.
Steps to Reproduce
Build a shower, have a puddle around it.
This issue has not been confirmed by a developer yet.