I once ended up in the same room as a pair of people who had been sending me death threats over the net. It was amazing.
This is back in 2002, when I was the head admin of a major UK-based Counter-Strike league (Barrysworld, for those with long memories of the UK online gaming scene). This is a good way to make enemies - you can never manage something like that without upsetting people and the Counter-Strike community (back then at least) had more than its fair share of immature pricks.
Anyway, there's one particular clan in the league which, towards the end of my first season in charge, is picking up a real reputation for hurling quite nasty abuse at their opponents before, during and after games. After one of my admins passes me screenshots showing some really nasty stuff in-game (vitriolic racist abuse) during their latest match, I throw them out of the league.
This does not sit well with them, particularly as they were in with a shot of winning their divison at the time. There's the inevitable IRC explosion, resulting in a series of quick channel-bans. Then the private messages and e-mails start up. Two of their members do not want to let this drop and, for the next month or so, I get a string of abuse from them. It starts with insults, but when those don't get a response from me, ramps up to threats. They're going to do unspeakable things to me, to my parents, my grandparents, my dog (I don't have a dog, but hey) and so on. And... I ignore it. Actually, no, I have a good laugh at some of it (it's very much in the camp of "a 16 year old's idea of what scary sounds like).
And then I go with my own clan to a big LAN party - one with a whole UK-profile, in a major venue, split over three days. And I meet up there with some of the other people involved in the league. And one of them mentions to me that my two little stalkers are both present at the event.
So I go over. And I introduce myself. And I am lovely and polite. I smile lots. And I remind them, in a "ha ha, isn't this all funny" manner of some of the things they've been saying to me.
I am not physically imposing in any way. Tall, yes. But kinda scrawny as well. I don't think I'd have a clue how to even go about making myself look intimidating. But I've never seen two people look so scared in my life. I think it was just the acute social discomfort I was causing rather than any kind of menace.
It was utterly hilarious. Never heard a squeak from either of them ever again.