I learned some squirrel language when I was younger after one followed me and my friends through the woods purposefully pelting our heads with acorns for 20 minutes.
It’s surprisingly easy to mimic a few of the more common noises. The main ones are pretty well documented as well.
People who like squirrels should get degus. Degus are not propely squirrels, but close cousins, and they are brilliant pets. Their intelligence is outstanding.
I fed my squirrel today. They bring me so much happiness.