What is Bran Muffin?
1.
When you are calling someone the shit because bran muffins give you the shits
That girl is a bran muffin
= That girl is the shit
2.
A phrase one uses to describe the typical vacuous, blonde, trashy
What's he doing with that bran muffin? Granted, she's pretty hot, but she's a total moron!
See