User blog comment:DarkCreeper/New Spooky laugh on PBE, what could it be?/@comment-5077844-20150602222109

Obvs a new champ.

Same as with Bard. They add werd stuff to the map, don't explain it, let it go live, and after that the new champ gets revealed.

From the sound of it, it looks like we're getting some underwater kind of guy, which also ties in with the coming Gangplank rework and the Miss Fortune Vu for a big bilgewater + maybe shadow isles event (because those things are enemies since Kalista reveal)

If it's really just a  teaser for Gp's update (which won't even be THAT big), than Riot has way too much time on their hands if they put unnecessary "easter eggs" like this in the game.