tip of the berg
When a girl's buttcrack is peeking out of the top of her pants. It's basically the opposite of plumbers butt because in most (not all) cases it's not a bad thing.
Dude, check it out. It's the tip of the berg.
tip of the berg
When a girl bends over or when her pants just hang too low and the tip of her crack peeks out over the top. It's very similar to plumbers butt, except that sometimes it isn't gross.
Dude, check it out. Now that's the tip of the berg.