When my son was really little (1-2), he wore those very form fitting PJs that have cuffs the size of my wedding ring. Invariably, he would spread his fingers into jazz hands every time I tried to out those darn PJs on him, and get his poor little fingers caught. But, when I tried to put gloves on him, he would ball his hands into fists. Basically, his hands would do the exact opposite action I needed him to do to get dressed easily. So, I started saying "pajama hands!" and making exaggerated jazz hands any time I needed to get gloves on him. Even though he wears loose fitting PJs now, we still say "pajama hands!" when getting dressed to go outside.
My son is now 4. Yesterday, we were playing "name that emotion". I would make a face or gesture, and he would have to identify what emotion I was feeling. So, smile means happy, furrowed brow means confused, etc. For this turn, I smiled broadly, opened my eyes wide, and threw my hands in the air (excited), and he yelled out "pajama hands!"