You can get a cheap packer online if you don't already have one. I had a coworker brush against me at the register last night (and I happen to have the hots for her, it was pretty horrible) and her ass rubbed up right against my packer... No idea if she noticed by I sure did. Either way, if you're going to be in a situation where you're likely to be grabbed or rubbed against, a packer's not a bad idea. I have no idea if people actually notice that kind of thing. I grinded with a guy once (yeah, only once... I don't dance and I'm not really into guys.) and I could have sworn he had nothing there even though a couple friends have told me all about his goods... -_-'
It's up to you. If you don't have a packer, a couple of rolled up socks in tight briefs should be fine. A small bulge might add confidence too. Not too big though xD