I wrote it better here:
"Magnar has hacked the DIKs laptop: This theory came from the thread, not from me personally. It suggests that Magnar has hacked the code of the "Brawler" app to gain remote access to the DIKs devices. In this theory, Nick was in the right place at the wrong time during the party when the Cathy cluck was first posted. When Nick was using the laptop during the party and logged into the DIKs cluck account, Magnar could remotely post the cluck which would frame the DIKs and Nick became an unfortunate scapegoat. This theory tracks with what Nick has told us, that he was with the laptop during the party but that he did not post the cluck, and also means that the image of magnar editing the brawler code has a pay-off in the story.
"Nick made a mistake" theory: In the aftermath of the Cathy cluck being posted, Tremolo explores the DIKs mansion to talk to all of the DIK members and Nick is found alone in the library. The theory here comes from Vinny and Nick's connection as maggot brothers and a shared hatred. Nick wants to get back at Tommy for the way that he treats Tommy and similarly, Vinny wants to destroy the DIKs. In this scenario, Nick opens the window to the library, letting Vinny into the party and allowing him to post the Cathy cluck. This theory also means that Nick is not lying as he was with the laptop, however, it was Vinny who posted the cluck"
