The best funny bumper stickers are all here including great removable magnetic prank ones! Shop Adult Humor Bumper Stickers from CafePress. Make a statement with tons unique designs or create your own custom bumper sticker with text and images. High quality printing on durable, weather resistant vinyl. Here is some adult humor found in Cars films. Contents[show] Movies Cars () When everybody notices that Lightning McQueen was missing after Mack arrives in California, Mack asks "Did I forget to wipe my mud flaps?" This might mean he forgot to .