Aiyyaa, in Tamil, means sir, a respectable person, may even be used for father (actually appa in Tamil) at times.
But then that's not exactly how's it's used here in the name of the movie. Aiyya is a common form of expression to express surprise, shock, or something of that kind, and here it means that same one. I mean, you see something n suddenly blurt out, 'O My God!'. Here Aiyyaa is something like that only.