1) When someone 'deadens' or 'kills' an ongoing joke.
2) Can also be used to describe someone who frequently 'kills' jokes, creates awkward situations, and is just generally cringey. This person would then be known as a Graze.
1) *everyone is laughing at ongoing jokes and conversation, someone adds in an unfunny comment that stops everyone laughing* - "man, you just Grazed it."
2) "oh him? don't invite him, he's the biggest Graze"