Eleanor has a couple of toys that make crinkly sounds, and she loves them an absurd amount. She is sort of hilarious about them. The elephant ear on her playmat, for example. She'll flail an arm against it by accident, and then you can see her spend the next minute trying to figure out what she did, and how to reproduce it.
And then we went to the doctor for her poke-and-prod (11 lbs 9 oz!) and she's lying on that sheet of paper they pull out for each new patient and she squirms and it crinkles and she is like WAIT A MINUTE. THIS IS AMAZING.
Over the moon, this one.