Tons of joke answers and few actual answers, so here's the opinion of an ex-cop:

What's your aim? If it's to identify ICE via speed dating or something to collect a list of local ICE agents, it'll take weeks, months, or even years years to uncover what they do. ICE agents know quite a few people hate them, so they're not going to wear their job on their sleeve. In that line of work it's known as OPSEC. In my personal life, very few people know I was a cop. ICE is even less popular, so they'll be even more tight about it. Best advice on this front is just keep your ears open for claims of being "taxi drivers," "garbage collectors," or other jokes cops often make to describe what they do.

If it's to avoid dating/befriending ICE agents, all you need to do is let it be known that you hate ICE. Obviously your HR is going to come into the fray if you're passing out "FUCK ICE" pamphlets, but feel free to get tattoos, bumper stickers, T-shirts, and whatever else you can get your hands on to express yourself, and I promise you ICE agents will avoid you like the plague, though they won't outwardly state their reasons why.

I don't want to hang out with people who hate me, you don't want to hang out with people who hate you, and ICE agents don't want to hang out with people who hate them. Not only is it unsafe, but it's simply unpleasant.