India, July 10 -- Well, well, well. Big Brother fans, the game just got a huge shake-up. Season 27 officially kicked off, and yes, that mysterious 17th houseguest we've all been speculating about? They're already inside the Big Brother house. And no, we still don't know exactly who it is. But the reactions from the other houseguests? Absolutely priceless.

Entertainment Weekly's exclusive photos show the moment the mystery guest entered, jaws dropped. Literally. Ava's face says it all. Dressed in a laid-back hippie-style hat, she looks like she just saw a ghost.

Right next to her, Morgan is mid-reaction, swinging an arm that screams, 'What is happening?!' It's dramatic, chaotic, and pure Big Brother.

Then there's Zach, who was apparentl...