Mark: I'm not coming to the party. I hate parties and I don't like being with other people. You should stay at home too. It will be so boring.
Kevin: Don't be such a wet blanket. It will be fun!
Wet blanket - English slang for someone who is miserable and that tries to make other people unhappy too.
lol, nice Slang to be learned! thank you very much Teacher :D
I hope i won't never be a wet blanket.
I'm sure you won't be! :)