How to you write "heads up"?

“Heads up” meaning advance notice or warning. I have always felt it should go in quotes:

Hey, thanks for giving me a “heads up” that my ex will be at that party this weekend.

Hey, just as a “heads up” there’s a serial rapist waiting around that corner, you may want to cross the street and take a different route.

Recently, however, I’m feeling the quotes to be cumbersome and it seems it’s a common enough figure of speech that it doesn’t need to be highlighted. Still, when I right it in a sentence without quotes, it looks to me like it would make the sentence difficult to parse on the first read through.

I don’t think I’ve ever seen it in quotes.

Wow. I wrote “right” when I meant “write”. Not really sure how my brain made me do that.

I can’t remember whether I’ve ever written it and if so, how, but my impulse would be to hyphenate it:

“Hey, thanks for the heads-up on that!”

No scare quotes, no hyphen, no apostrophe.

twickster, professional writer/editor

Hmmmm, I wondered if someone might suggest a hyphen. I could see myself going that way.
Thanks for chiming in, twickster. I thought there might be a GQ type answer, but I posted in IMHO since it’s an expression used quite casually- I figured there’d be a range of personal style choices since the majority wouldn’t be writing in a professional context. All due respect to your expertise, and your enlightenment on the matter has been noted.

I would hyphenate it.

No hyphen. Why would you hyphenate it? Would you say “Thanks for giving me a wake-up this morning?” (The answer should be “no way!”) Perhaps a “heads-up notice,” but unless the phrase is modifying another word, no hyphen.

Why on earth would it go in quotes?

Sorry, but “way”. And similarly, I’d say, “Coffee is a great pick-me-up,” and “I hate to wear hand-me-downs.” Would you say “Coffee is a great pick me up,” or “I hate to wear hand me downs.”?

But those are different grammatical constructions. “pick-me-up” is a single phrase modifying “coffee.” “Hand-me-downs” is a better parallel, because at least it’s a substantive.

“Hand-me-down” is a noun constructed from hand (v.) + me (ind. obj.) + down (adverbial use of a preposition, here modifying “hand”). The up in “heads up” is the same kind of preposition-turned-adverb, but the verb is unstated and there is no object. “Up” doesn’t modify “heads,” except in the looser sense of predicatively, so no hyphen.

I am not a linguist, and it’s pre-caffeine, so I can guarantee I’ve made a typo or used the wrong phrase, but on preview I can’t see where.

How I would write it:

FYI- There’s a serial rapist waiting around that corner, you may want to cross the street and take a different route.

My reasoning always followed thusly:
From the Wiki Article on Scare Quotes, Sub-section “Neutral Distancing”

I have not studied the origins of “heads up” but, in my mind, I always had the idea that it originated in gym classes or team practices when someone wants you to catch the ball hurtling toward you rather than get hit in the face with it.

So, basically, in my mind it is colloquial folksy slang usage of gym class jargon applied metaphorically. Metaphorical since, outside of gym class, there is no literal ball to be caught and no literal being hit in the face (hopefully).

It is neither colloquial nor folksy and I really doubt it is jargon.

It looks ridiculous in quotes. Or should that be “quotes”?

Seriously, bienville, what the hell is wrong with you? How could you ever follow a line of reasoning that might bring you to a conclusion that differs from amanset? How does your brain function anyway? A word of advice, bienville: next time you feel compelled to share your thoughts on the internet- don’t.

Glad we’ve got that clear then. You’ll find it all a lot easier now.

Knock it off, you two.

Sorry. From my side, it was in jest, but heard and understood.