So simple, yet so funny

Why is it when someone puts their jumper on backwards, it's funny? Something so small and so simple and yet A has done this several times recently. It's because his jumper is already inside out and he gets it the wrong way around when he puts his head in. Still, as it's a V-necked jumper, to see him looking all "clerical collar" with the rounded back at the front and the V going down his back still makes me chuckle.