We're nothing if not practical here at Parent Hacks. Tell me if this hack doesn't revolutionize bathtime at your house! From John:

We've completely eliminated the need for bath toys when traveling (and at home) by conjuring big bubbles from thin air. With baby shampoo
on my hands (straight from the bottle, it is too hard to get the right
consistency once it has been on a kid) I rub my hands together to get an
even distribution. I flatten my hand with all the fingers together and
then curl my fingers over into a C. At the same time I slide my thumb
along my pointer finger to the tip creating a film of soap in the
circle formed by thumb and pointer finger. (It's important not to pull
the thumb's tip away from the pointer finger.) A light blow (the more
dramatic the more magical) and then slide the thumb back into line
with the hand to close the hole.

Voila! I'm magic! And there's nothing up my sleeves. (In fact, sleeves
just get wet. :)

Related: Lots of great tips in the Bathtime archive.