Crotch-staring is the only answer.

So guys tend to have a fascination with the female body (as recently noted on the post below).
And that's great, really. I do too.
But what isn't great is being in public, meeting someone, talking to a coworker (especially awkward managers named Bill), catching up with a friend you haven't seen in a while, ordering a drink from a bartender and absolutely knowing that they're looking at your (my) breasts.
I will never let you walk by me saying 'it's a compliment, shut up.'
One time I was talking to a group of guys and I sighed heavily in annoyance of some passer-by in my peripheral who 180'd me (this sounds like I'm getting at how hot I am but this literally happens to any walking vagina (haha imagine a walking vagina)("oh, i'm going to take my vagina for a walk")) and the guys I was talking to were like 'I think girls actually really like getting checked but they have to act like they don't; it's like... playing hard to get.'
My talking to these guys just happened to be on the fifteen minute break in my women's studies class and my head was feeling hot with petulence and disfavour.

So -
it's not okay, it's not acceptable, I have a face and all women usually do so please be a decent human being as I invite you to look at it.

And while you're trying to figure out where to look when conversing with me, I'm going to look directly at your crotch, asshole.
I hope you feel supremely uncomfortable with this gesture and shift your body around and make snide, giggly (to cover up the insecurity) comments where your voice will crack and you'll feel self-conscious about what I'm doing and how it makes you feel weird.
And of course feminism has a thousand million kadrillion ways of theoretically or professionally approaching the patriarchal issues of male control, male domination and the objectification of women - many of which I'm very fond of but there are a thousand million kadrillion ways that women can apply small solutions to these issues to their everyday lives.

I encourage any and every lady to do this as well and encourage everyone to watch this short video:
http://www.youtube.com/watch?v=jO9p6e4SWLM