"Hokahey" is a man's exclamation in Sioux, similar to the American expressions "Let's do it!" or "Let's roll!"
The reason people think it means "it's a good day to die" is that the Lakota Sioux leader Crazy Horse famously exhorted his troops "Hoka hey, today is a good day to die!" Which meant something like "Let's go men, today is a good day to die!"
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.