High Voice
When Josiah is tired, he likes to talk in a really high voice. It isn't quite a squeak, but it is at an octave that humans don't tolerate well - at least adults. Thaddeus finds the high voice rather amusing and it is pretty much the only way Joe can get Thad to laugh, despite trying to do everything Eila does to bring out the giggles from his baby bro.
Lately, he has also been pretending to be a baby bird with a very high-pitched tweet. He loves the idea of eating worms and being in a nest and then flying out at random, when mixed with a high voice who can resist?