a slang word used to stop someone from saying somethingnegative about another person that isn't around to defend themselves.
Josh said "Wow, did you see her outfit, she looks like she just came from the dollar store and they didn't even have her size" Grant said you need to "Squash it and be nice!!"
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.