crashtag
The hijacking of a hashtag that is used specifically used among a group of friends for their own photos and status updates on social media sites by introducing unrelated content and tagging it with said hashtag.
When Andy's girlfriend was living it up at a bachelorette party in Las Vegas, all the men decided to go to the local bars, take pictures of themselves getting wasted, and crashtag themselves onto #JensWildVegasParty.