A female who is a secret lesbian. She may date, shack up with, and/or flirt with guys but deep down she has a strong passion for females. She is still in the closet or in this case the "lunchbox" She thinks your mom packs better stuff and wants a peek inside and possibly a taste.
"Kristen your boobs look really nice in that top" "Carol you're such a lunchbox lesbian! Stop trying to touch them"