PJs

You know what's a really odd word? Pajamas. It's such an everyday word, yet has anyone questioned its usage until I just did? Actually, my family has rejected the word and replaced it with "sleeping clothes." It makes perfect sense: clothes you sleep in. However, it provides great imagery of clothes that are actually sleeping themselves.

In order to provide answers as well as questions, I just did some research for you. Apparently, the word pajamas (also spelled pyjamas) comes from a group of pygmies in Africa that used to make tiny clothes out of leaves and bark to wear while they slept in order to protect them from the cold.

...Not really. It's actually derived from the Persian word Payjama meaning "leg garment."

The other answer made sense, though--you believed me, right?