When a person runs out of ideas for places to visit on the internet - email's been checked, no one's on facebook, etc. This can lead to staring blankly at your computer screens or resulting in visits to sites like chatroulette or 4chan, just to waste time.
Guy 1: ... *staring at computer screen*
Guy 2: Dude, you ok?
Guy 1: Yeah, I just have troller's block.
Guy 2: Oh that sucks. Have you tried lemonparty.com?
Guy 1: No, but I'm desperate, so I'll check it out.