This puzzle's theme and a hint to 20-Across20AWhy do bicycles fall over? Because they are _________[--------], 26-Across26AA cross-eyed teacher couldn't control his ______[------], 29-Across29AWant to hear a joke about paper? Nevermind, it's ______[--------], 42-Across42AMy dalmatian got away from me and ran through a car wash. Now he's _________[--------], and 37-Down37DHow do mountains see?[--------]