Sonny Koufax (Adam Sandler) is a 30yr old law-school graduate who won a lawsuit many years earlier, and lives off the investment. He lives a bachelor style existence, and is happy to do nothing all day - but suffers grief from all those around him (except the delivery guy) who tell him that he is wasting away his life. Sonny's roommate Kevin (Jon Stewart) is off to China on a business trip, and while away a young boy shows up claiming to be Kevin's son. When he hears that Julian might be sent to orphanage, and in an attempt to win over the doubters and prove to others that he isn't a waste of space, Sonny decides to become a self-appointed foster dad to Julian - or "Frankenstein" as he prefers to call himself. The thing is, his plan seems to be working - and being a good dad is proving to be a hit with the ladies!

Sonny's life is changed around by the new little fella in hsi life, and suddenly he couldn't imagine life without him. He has a new focus in life, and even the Russian delivery man is learning to read!
  When the authorities catch on to what has happened, he is arrested for fraud.
  On trial, his defence lawyers include his girlfriend, his uni buddies, Jon Stewart back from China, and even his dad - although he is only called as a witness.
  Sonny gives a speech about how he wants to be a good father - and that his father always wanted what was best for him too, and that he forgives him. Everyone is moved by this, and even the homeless guy (Steve Buscemi), who was a character witness, phones his old man for a chat!
  It doesn't work and little Julian is distraught, but his real dad steps up (John Stewart) to save him from going back to the orphanage, and doesn't want to press charges.
  Julian and his real dad are properly reunited, and given Sonny's blessing - and a few tips.

It cuts to a time further down the road, where Sonny is now a qualified lawyer, wearing a nice new suit, and happy with his girlfriend. For his birthday his friends take him to Hooters, where he meets up with a happy Julian and family - and also his ex who is now a waitress, and her wrinkly boyfriend is one of the chefs. As he said, its an unexpected 5 year plan!