Whether it's allowed or not depends on the rules of the festival you're going to. Safe? About as safe as going barefoot on city streets, probably, with similar minor risks of stepping on broken glass or other sharp things. You won't die.
Tom Petty [Final Fantasy XV] (9%)
Bondage Finch [Bondage Finch Adventures] (12%)
Melisandre, the Red Woman [Game of Thrones] (43%)