The term "hydrogen hydroxide" means a hydrogen ion (H+) bonded to a hydroxide ion (OH-). when you put those together, you get H-O-H, which is of course H2O, which is water!
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.
We have a Zoom meeting in a few minutes and I’ll probably go pajama casual.