1. It's a substitute for any words that would not be appropriate for a situation.
2. A name for someone if they are acting like something that you can't say.
This is NOT the same as the word genre. Totally different. Johnra is more blunt. John. Ra. Genre starts with the Jean sort of thing (the French way of saying it)
"This crappy car is johnra."
"My 5th grade teacher was a johnra."