2. To troll someone with a meme.
3. A more recent replacement for "for the lulz!"
Taken from the early-2010 internet meme of the "Russian Rick Roll".
John: And so I went to the place with the guy and we did the thing and then this other thing happened so we met up with a guy in a place...
Jack: STOP TROLOLOING!
John: *Puts pedobear image on /b*
Jack: WTF, noob. Quit trololoing the forum.
Jack: Why did you set the maternity ward on fire?