A misspelling of the popular Japanese book/manga and movie called Battle Royale
If you haven't already seen the film, I suggest you go and see it unless you are really into manga then you could read that first.
To see what its about then read some entries on the Battle Royale definitions.
"Hey did you know how to spell Battle Royale?"
"No I don't, I'll try anyway and create a thread for a misspelt version on Urban Dictionary"
"OK fair enough."