An annoying faceless Internet "troll" (see sep. def.) who hides and targets people to harass and annoy in chatrooms and comment sites (i.e. YouTube") A "puppetroll" seems to be targeting people who hold or defend a specific belief system or political posture and who also are seemingly in collusion with others (of opposition discredit, defame and/or attempt to invalidate the opinions of others).
Examples: "My YouTube Video had a massive number of "Puppetroll's" today"; "The "Puppetrolls" are all over the Board Tonight eh?" "Damn you "Puppetrolls"!!" (may also be shortened to "DYP!")