Actor Ranbir Kapoor, who enthralled the audiences with his performance in "Rockstar", feels that sperm donation is a good cause.

"Sperm donation is a good thing. After all you are helping someone," the 30-years-old told reporters Tuesday when he was asked how he feels about sperm donation.

Ever since the movie "Vicky Donor" has come out, sperm donation has become one of the most talked about issues. In fact, during an act at the International Indian Film Academy awards in Singapore, Shahid Kapoor pulled Ranbir's leg saying he should donate sperm.

"When Shahid wanted me to donate sperm, I was backstage and I could not do it. So now it is on my priority list to donate sperm to him," said Ranbir humorously.

He was talking on the sidelines of the screening of Anurag Kashyap's directorial venture "Gangs of Wasseypur".

Those who couldn't enjoy the Shahid-Ranbir live performance at IIFA, they can watch it on the small screen. It will be broadcast on Star Plus July 7.