I came across the sentence in a comment from this news story.
The investigators are sharing squat. But I bet they know a whole a lot.
What does 'sharing squat' mean here?
"Squat" is slang for "absolutely nothing." It's presumably a euphemism for "shit." It's commonly heard in the expression "doesn't know squat," meaning "doesn't know anything [about this issue]."
"Doesn't know shit" is equally or more common, and means the same thing more emphatically. (And is vulgar, obviously.)