Chalk this up to things you've never expected. A Fortnite dataminer has been sifting through the game's most recent updates, and they've found something that might point to a Splatoon collaboration. The lines of code that are fueling the speculation can be found below.
Obviously Splatoon fans are going to see mention of 'SquidKid' and automatically think of Nintendo's series. That said, Epic might be using this as a name for countless other items in the game. It honestly would be pretty surprising to see Splatoon represented in Fortnite, but stranger things have happened!