I go to a lot of Jewish events in Philly. There's one person who comes to a lot of events, too, and he has really terrible body odor. It's hard to get near him. It's hard to avoid the smell if you're anywhere else in the room. He's a nice guy, but he has kind of an attitude, and I wonder if it comes from the way people treat him. I feel bad for him, but I'm not sure it's any of my business. Is there any good way to communicate with him about this?
A few weeks ago, I answered a question  from someone who went on a date with a guy who also stinks. I'm dying to know if there are multiple offenders hanging around the Jewish young adult community, or if I actually got two questions about the same person. Regardless, you're further removed from the situation than a one-on-one date, but closer than just being able to turn your back on this fellow.
A first step would be to identify if this guy has made any close friends through attending these events. Maybe he always shows up with the same wingman, or perhaps you've noticed that he tends to interact with the same two or three people at every event. If that's the case, you could use them as allies. As awkward as it might be, you might be able to call one of them aside and say something like, "I've tried to get to know your buddy over there, but I notice that he has a really strong body odor. Maybe you could mention that to him." Then you've done your part to help out, but the ultimate responsibility isn't on your shoulders.
If, like you, others attending events tend to steer clear of this guy for obvious reasons, then your options are either to get better at avoiding him or to confront him directly. I'm playing over and over in my head how you could actually say to someone you barely know, "You'd have an easier time making friends if you smelled better," and I can't see it happening. Instead, I'm envisioning some kind of middle school-esque note-passing. You could write a note that says, "You seem like a great guy, but I think you'd benefit a lot from trying out a new deodorant. I'm not saying this to be mean, and I really don't want to embarrass you. Please understand that I'm just an anonymous friend trying to help."
Since most of the events you're attending are probably staffed by at least one Jewish professional, you could enlist his or her help in getting the note into the guy's hands. It also may be worth talking in private to the staff member to see if he or she has any insights into something else that might be going on for this person that might influence his hygiene. If someone slips me a note at the next Grad Network event, I'll know what's up.