Apparently, the top definition tells us it means when a girl's ass is hanging out of her pants.
Instead of using normal words to describe this, retarded people from the mean streets of harlem or whatever, decided to use some "urban" funky words. 99% of the slang that exists is fucking stupid, i mean, what the fuck is shizzle my nizzle, for the good of humankind, if you ever hear that phrase mutter, shove your fist at speed into whoever said it's mouth.
This is stupid,
bad moon on the rise, is derived from the
Creedence song,
Bad Moon Rising. Its a phrase used to describe a bad omen, or bad things on the horizon.
Example:
When people
bastardise normal words for such a stupid phenomenon, i see the Bad Moon on the Rise.
Yeah, shut up with your stupid made up slang,
fuckfaces.