It is said that laughter is contagious. Is it true?/You don't say.

Yes, it's really contagious. Friends get together, talk interesting things, laugh all the time, and tears come out. Finally, their expressions became stiff and they didn't know whether to laugh or cry. Some of them came in later, and I don't know what happened. Seeing that we had been laughing, I giggled. Originally, it was a very funny thing, and it will end in a moment, but we still, look at him, and he looks at you laughing all the time, as if it is no longer because of the funny thing just now, and we are all smiling at each other and infecting each other.