You don't....call it "folk art" and let it go at that!
The skin is pretty easy,a couple of days and it will be gone....but the khakis...
You could mess with goof off and other stuff, but unless they were new, I would call them play pants.
Linda C

I can't help with his clothes, but some corn oil or safflower oil from the kitchen, rubbed into his skin, will help with the paint. It's also very kind to the skin. I agree, the pants are good only for the next paint job.

Count yourself lucky. Years ago, my niece was painting her bathroom red when she had to stop to get ready to go to a meeting. She placed the lid on the paint can and pushed it to a corner of her bathroom. As she was sitting at her vanity, she heard her 18-month-old come in behind her and say 'Wa-Wa" and then "Oh Oh, Wa-Wa". She turned around to see that he had spilled the entire can of red paint on the carpeted area of her dressing room. She watered the paint down hoping to make it easier to get up, and started vacuuming it with the wet/dry vacuum - only to discover that she hadn't connected the hose correctly and was spraying the watered down red paint all around the room! Talk about a mess!