Taken literally...

The anatomical implications of the phrase “watch your head” are somewhat disturbing. Well, maybe you could cheat with a mirror, but you’re usually told this when you don’t have one readily available.

Good point. That’s sort of disturbing, actually.

I knew it - I read your “disturbing” phrase, then used it as my own! That ALWAYS happens! Errrrrgh. Let me think of an original thing to say.
That’s quite interestingly odd.

Good point. It’s kinda odd, actually.

Actually, it’s kinda oddly disturbing.

Actually, if you’re a man, and you did take it literally, you’d be complying with the intent of the warning - ducking.

So what if you’re a man and you take the expression “Heads up” literally?