Whistling Teapot
It is when a girl is on her rag and is using a tampon. It can only occur in hot temperatures or in a heavy workout. The girl experiences a whistling teapot when the heat causes her vagina to steam thus making her vagina boil over and produce a slight whistle. The tampon acts as the teabag in the analogy.
The girls vagina spilled over because it was a whistling teapot.