Haha well it's an interesting language and definitely not the easiest one to learn, so prepare to spend some time should you dive deeper into it! :D
One could say "oletko ihan pöllö?" - "are you a total owl?" meaning "are you stupid?" (silly/dumb, in a softer way), or "ei pöllömpi idea!" "not owlier an idea!" meaning "not a stupid idea!". Not a commonly used expression though.