After you.... NO after you! >=(

After you I think is a lesson to not be too incredibly nice. If someone is extending their kindness to you, accept it with thanks and get over yourself. Now this could have been both  characters in this film. The yellow character could have went through the door and accepted the "Kindness" of the blue character. But instead the yellow insisted he blue should go first and thus begins the endless cycle of "Kindness". Although I could be missing something this is how I interpreted it. And even after the blue character ripped off the yellow ... turtle's(?) arm he got the door slammed in his face. Which the blue character could have avoided by just going through the door.