Every kid imagines what it would be like to be an adult. He wishes he could grow up quicker. Of course, once he grows up, a small part of him wishes he could go back to his childhood days. Quite an irony, isn't it?
There's a line in AAO WISH KAREIN that goes, 'If you want to be a part of a fairy tale, it's important that you believe in it [fairy tale].' The statement is applicable for everyone desirous of watching AAO WISH KAREIN.
In terms of concept, AAO WISH KAREIN bears a striking resemblance to the Tom Hanks starrer BIG [1988]. A decade-and-a-half ago, the Salman Khan - Sridevi starrer CHANDRAMUKHI also tackled a similar theme. In that respect, the concept isn't alien at all.