Bachchan, 72, donned a white blazer and blue-faded denims with his grown beard and hair and sang the two-and-half minutes song on the toilet seat.
"#Shamitabh... Okay here it is... PIDDLY SONG...!! Enjoy,"
Bachchan posted on Twitter along with the link of the song.
T 1723 - #Shamitabh ..OKAAAY HERE IT IS .... PIDDLY SONG .. !! ENNNJJJOOYYYYYY ..
— Amitabh Bachchan (@SrBachchan) December 31, 2014
As the first song of the R Balki-directed film proceeds, the actor is seen using the hand shower as his microphone. The foot-tapping song has so far bagged 173 likes on YouTube within an hour of its release.
"Aankhon se padhne mein hi hai nasha. Nashe ke saaye mein. Sab piddly hai yaar. Piddly si baatein. Kyun karti ho Sharma ke....," the lyrics goes.
Last week, Bachchan released the first audio poster of the film, which features other starcast including Dhanush and debutante actress Akshara Haasan. The film is expected to hit theatres on February 6, 2015.
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Bachchan has earlier lent his unique baritone in 'Bol Bachchan', 'Don', 'Bbuddah Hoga Tera Baap', 'Kahaani' among others.