An anonymous hacker, known only on Twitter as @WauchulaGhost, and a few of their friends hijacked several Twitter accounts that were known to be associated or in support of ISIS.  This has been going on for a few months, @WauchulaGhost is apparently affiliated with the "hacktivist" group Anonymous. After the attack in Orlando, they and some others have stared adding rainbows, messages saying "Out and Proud" and even some links to gay porn to these compromised accounts. According to Newsweek, the hacker claims to have taken over at least 200 accounts and plans to continue this campaign. 

What the sign should look like: