Saif Ali Khan has formed a deep friendship with director duo Raj Nidimoru and Krishna DK in the last few years. Having done 'Go Goa Gone' last year, the trio has now come together for 'Happy Ending'.

While shooting for the film, Raj and Krishna got to know that Saif is a fan of Joker, the character from the Batman series, reports Times of India.

Since the actor's birthday was around the corner, the two bought a rare life-size Joker toy and gifted it to him. They also threw a birthday bash, where Kareena Kapoor Khan was invited, along with the entire cast and crew of the movie. Says the director duo, "Whenever we had a brief break during the shoot, Saif used to sneak out to book and comic stores.

So, we decided to gift him the life-size doll of Heath Ledger's character in The Dark Knight on his birthday. It's a limited edition Joker doll and Saif was thrilled to keep it as a collectible."