"they" is nobody, "they" is whoever told them something or gave them advice.
'They' is a referring to (generally speaking) everyone else, i.e a collective opinion / piece of advice etc that is put forward / offered, on the basis that it is the collective opinion of a large number of indeterminate other people.
You say: How to you say It someone says: IT you say: no I....T
if someone says your funny just say lol i know. lol get you out of everything.
say hello
"I know."
You don't answer them, rhetorically speaking.
If a person says they like someone will spend a lot of time with them.
when someone says hello you also say HELLO, hahaha der!!
When someone says congratulations to you, or when someone congratulates you, say, "Thank you".
The same thing you say when someone says "you're welcome" - nothing.
sarcastically say, "oh really? I didn't know that."
It means exactly what it says...to write about what you know. If you know about something than you'll have more to say and have an opinion. If you don't know about a subject...there's less to say.
It is called sarcasm when someone says the opposite of what you say in a mocking or ironic way.