This next one is quite hard for me to explain, but I'll try my best.
When I am excited, I interlock my hands like this:
(best image i could find)put the middle knuckle to my mouth and make a squeaky/squealy noise (kinda like a mouse
). I have done this since I was 2 years old. I still do it to this day, although since mid-primary school I have controlled it in public and only do it when I'm on my own.