The challenge is on. Castro fans are decorating their cars in support of their favorite Idol. Aggie Mom Nancy Belew was the first to send us this photo of her rolling billboard.

Paint your windows and then drive on over to the HiltonBellaHarbor in Rockwall tonight for the next American Idol/Jason Castro watch party. We may feature your decked-out dreadmobile on our next neighborsgo watch party video.