When Ajay Devgn approached his close buddy Salman Khan to do a cameo in his Son Of Sardaar (SOS), the latter immediately agreed to do it. In fact, Salman had made Ajay listen to the song, Po Po, a long time ago.

Ajay liked it so much that he asked Sallu if he could use the song (a perfect combination of Punjabi tadka and masti), in his film, informs a source close to the duo. And Salman, who's known for his generosity, readily agreed.