How did Joey find out that Monica and Chandler were dating in Friends?

Haha, Friends...it makes me laugh when I think about it

First of all, Chandler said that he met a celebrity named Donald Trump in the hotel while waiting for the elevator. Later, Monica also said I met this man waiting for the elevator

Secondly, Joey said that the hotel called and said that there was an eyelash curler that fell in the room. Joey thought that Chandler had a female companion at this meeting or was attending a gay conference. Until Mo Nika said her eyelash curler was missing

And when they came back they were both angry and said the "meeting" didn't go well

These combined made Joey feel that it was not a coincidence. They were together at the time...

I don’t know if I made it clear, but it’s not very good if I don’t have the ability to express myself...