When someone posts a "what is this?" and someone else says "it's a______", other people who agree will just put x2, x3, etc rather than writing that they think it is what the guesser said it was. For example, if I post a pic of a chick and want to know the breed and someone posts a response that says "it is a buff Cochin", the next person who posts might post "x2" if they also feel it is a buff Cochin rather than saying they think it is a buff Cochin.