The word comes from puttana, but it is not clear the relationship between the meaning of puttana and the common use of "puttanata".
B: Che puttanata!
A: Do you know I can jump over 57 meters?
B: What a bullshit!
A: Ho fatto una puttanata: ho tradito mia moglie con la sua migliore amica.
B: I did a mistake: I betrayed my wife with her best friend!