Alya came to tell Marinette that She and Nino are a couple. Alya decides to face time Nino so he can see Marinette's reaction. She tells Marinette to wake up and then Alya notices that she was sleeping with Adrien.

Alya:"Gurl what the ..How??"

Marinette:"Uh Wait i was sleeping with chat noir not adrien That means"

Adrien/Chat Noir:"Hm? Princess? Uh-" realizes he detransformed while sleeping

Alya:"WAIT! You were aleeping with CHAT NOIR?.. How?? Also Adrien is Chat Noir??"

(Your Adrien)