Baccha kya? ;)

Song: Main Tera Dhadkan Teri
Movie: Ajab Prem Ki Ghazab Kahani
http://www.youtube.com/watch?v=zYV9G38YKCk&feature=related

I heard: Yeh din tera raatein teri ab baccha (child) kya, ab baccha kya
Actual: Yeh din tera raatein teri ab bacha kya, ab bacha kya

Thanks for correcting me, Ayesha!