It's the most popular song we sing at birthday parties, like your "Happy birthday" song. But I'm not sure it's pretty good for your friend. As you said your friend is a man (maybe a boy) and some Iranian man think it's a song for children. :) "Tavallod, Tavallod Tavallodet mobarak Mobarak, Mobarak Tavallodet mobarak Labet shado delet khosh To gol, por khande bashi Biya sham'a ro foot kon ke sad sal zende bashi Tavallod, Tavallod Tavallodet mobarak Mobarak, Mobarak Tavallodet mobarak" :)

The most papular song is which sama wrote. And phrases: Tavalodet mobarak. Omidvaram sale jadide zendegit por az movafaghiyat o shadi bashe. Behtarin ha ro barat mikham. Or: (these are more matey :D ) Khoshhalam ke be donya umadi. Donya ba to jaye behtariye.

tavalodet mobarak