Under the Mud (2006)

The Potts household is second home to a teenage slacker, Magic. He is such a part of the family that his longing for the eccentric beauty Paula Potts goes completely unnoticed; to her, he is just part of the furniture. As the family head towards self-destruction, thanks to an old enemy and Paula arguing with her imaginary friend about running off to Ibiza with a local slimeball, Magic realises that he only has one day to save the family, get the girl and change all their lives forever.