The top one is intentionally funny, but the bottom two are unintentionally so. Most English-reading people who understand metaphorical language would laugh at the top sign if they were standing at that urinal. But the middle, unwittingly a double entendre, conjures an image of David spying on Bathsheba as she bathed, and the bottom one is more like a solecism, evoking a scene too revolting to explain in this blog.
How do we guard against creating such unintended meanings and logical errors? The wicked side of me would answer, "Why guard against them? They're funny. The more, the merrier." But my professional side must say that in serious writing, from business messages dramatic scripts to novels, we should avoid them, and we can do so by carefully examining syntax (word order) and diction (word choice). Errors in semantics are most common when we are rushed or careless. All the current writing tools notwithstanding, including AI, we need to make a final careful read before pressing send.
