Effect:

A super kidshow bit of business.

You show a blue hat, which you place on your young helper's head. Oops, it's too small ... so you expand it into a bigger green hat.

No, still too small ... so you make it into an even bigger red hat.

Not big enough (by this time the hat is getting ridiculously large), so you expand it into a bigger polka dot hat.
You do it again, and turn it into a giant striped hat!

And, when you turn the striped hat around, there's a really funny Giant's Face on the other side that'll make the kiddies go bananas!

Silk screened on a special bookbinder's material, made from plastic and very strong -- use it over and over again.