Why do men on this chamber use the line “Shes 15 hello!?”

Whenever I see it, its just in response to what an adult man thinks of a random picture of a 15 y.o girl posted. I get that its the internet and people can claim any age they want, but it just gets on my nerves bc girls my age are not that and I can tell the difference. At least I can, can't really speak for anyone else.