Let's explain another word that came out of American anime fans. Unfortunately I don't have a first-person account of the creation of the word “glomp”, but I know what it means as well as anybody else.
You know when the schoolboy protagonist walks through the door, and one of the five or six girls in love with him is so delighted that she runs up and hugs him so hard she tackles him, usually while yelling his name adoringly? “Kenji-ku~n, let's go have lunch on the roo~f!!” That kind of stock scene.
Because they love to live in their fantasy, sometimes you'll see American anime fans try and do this in real life. It's not common practice, but it happens. The scene was being re-enacted on the floors of anime conventions before anybody actually came up with a word for it.
I'm not sure why the word “glomp” was picked: is it supposed to be the sound of impact? Is it the sound of the person being hugged hitting the ground? I don't think anybody knows anymore. I don't think anybody knew when they came up with the word.
I hear about this a lot more than I ever actually see it happen: it's an easy thing to joke about. There's a lot that can go wrong, you see, when one tries to do things one saw in anime in real life.
You're supposed to ask permission, for example, but that doesn't always happen. Some folks overdo it: they actually run fast and tackle hard and think that nobody could get hurt. You're supposed to ask permission, but again, some folks don't think that's required. The worst possible encounter, of course, is some total stranger running from out nowhere screaming broken Japanese and tackling you to the ground from behind.
Cosplayers of popular-in-America bishounen characters, like the casts of Full Metal Alchemist, Hetalia, or Ouran High, should be actively on their guard at the American anime convention. Being tackled by an overzealous stranger is actually very likely to happen to these people. Asian men with wavy hair and boyish good looks are advised to just wear masks.
As for myself, I've been glomped one time. After a night's drinking with friends, a new acquaintance turned to me and asked “Hey... can I glomp you?”
“Aw, hell,” I'm thinking. “This is a street corner, and we're both drunk. She is going to tackle me into oncoming traffic.” But we were both drunk, so I said “sure!” And she backed up a few feet to get the proper running start.