Make sure you are holding your friend's tentacle so you don't get lost: Willis, Jeanne. Dr Xargle's Book of Earthlets Pictures by Tony Ross.

If you only ever buy one sf picture book for your child, this is the one to buy. It just can't be beaten.

An alien teacher stands in front of his class and prepares them for the school trip to earth where they are going to meet earthlings. The lecture is full of creative misprision, and I can't write out the whole book, but here is ny favourite example:

[picture of baby wrapped in brown paper]

To stop them leaking, Earthlets must be pulled up by the back tentacles and folded in half.
Then they must be wrapped quickly in a flufy triangle or sealed with paper and glue.