A slang of slang for "sawbuck", a 10dollar (or equivalent collection of U. S. currency) bill.
"We
rigged his room with a one-way whorehouse mirror and charged a sawski to
watch it." (Here, the novel, "Naked Lunch", describes selling tickets to watch a snitch through a one - way mirror get euthanized via a poisoned shot of dope.)
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.