Prevalent among Southern frat boys, these nylon, leather, or neoprene strings attached to sunglasses, usually Oakley's, Ray Bans, Maui Jims, or Costa Del Mars. When the shades are predictably placed on the back of one's neck, the string resembles a necklace. Sometimes they are referred to as "Croakies."
"Dude, did you go to the Carolina Cup this year? I've never seen so many frat necklaces in one place."