To pull a Riley

To interrupt an ongoing, text-based, conversation by sending a screenshot of little to no connection to the topic at hand, thereby disrupting the flow and leaving everyone confused.

A: Did you read the chat from yesterday evening? It was hilarious, everyone was having a blast!

B: Yeah dude, it was great. Until someone sent that pic of their Clash of Clans base, why did they have to pull a Riley like that?