I'm in a chatroom and some troll is screaming about how he can send a virus to peoples computers from the chatroom itself. Is that even possible?

No. It’s not possible. He has no direct access to your computer. Just don’t click on any links he posts.

So more of a twatroom then, at least in that morons case. On a happier note, welcome to fluther.

“troll”
‘nuff said, really. If he could really do that, and he would really be willing to do it, I reckon he probably wouldn’t be telling you about it, he would have done so already. Although of course predicting trolls is not an exact science.
More importantly, what @MrItty said. I’m fairly certain this is not technically possible.

Depends on your web browser version, plugins and operating system. For example, Windohs and M$ Outhouse used to have an “enabling technology” (cough) bug where a program could be inserted into and to and run from an image, which could be posted to a forum. Probably not happening in the case of such a troll, though.

You know it’s a “Troll”...
But don’t know if this troll can send a virus…

Chances are the chatroom you’re using uses javascript, so it’s theoretically possible that javascript-based attacks could be employed. It’s really unlikely that he could target you with these attacks, but I suppose it could happen if he got hold of your IP address. It would be extremely difficult if not impossible to give you a virus in any case.