The act of justifying ones actions using childish rules commonly seen on a playground. Typically used in adult environments. When one calls playground rules they are entering a verbal understanding that playground rules is now fair game.

Play ground rules: finders keepers, you touched it last, no take backs...etc...
John: I found this really nice stapler in the office today and I took it

Bob: hey! That's mine!

John: playground rules! Finders keepers! It's mine now!
by Danie March 10, 2015
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