Hashflags for #Pride2015 were enabled on June 26, 2015 after the US Supreme Court Ruling on Same-Sex Marriage. The announcement was made on the Twitter account for The White House.
These hashflags displayed either a rainbow heart emoji, or a gay pride flag after typing the relevant hashtag. Disabled on June 28, 2015.
❌ Disabled
Example Tweet
The #Pride2015 Hashflags appear like this when used in a tweet: