Buns

any of a wide variety of variously shaped bread rolls, usually leavened and slightly sweetened or plain, sometimes containing spices, dried currants, etc.
hair gathered into a round coil or knot at the nape of the neck or on top of the head in certain coiffures.
buns, Slang. the buttocks.
Contemporary Examples

The Humble Burger Goes Glam Katie Workman June 29, 2009
Real Housewives, Real Problems Amy Kaufman November 4, 2009
On the Peninsula Bryan Curtis April 24, 2011
The Perfect Homemade Burger Cookstr.com August 23, 2010
The 21 Worst Food Ideas Ever September 6, 2013

Historical Examples

The Believing Years Edmund Lester Pearson
Home Life in Colonial Days Alice Morse Earle
The Youngest Girl in the Fifth Angela Brazil
Sara Crewe Frances Hodgson Burnett
In Search of a Siberian Klondike Homer B. Hulbert

plural noun
(informal, mainly US) the buttocks
noun
a small roll, similar to bread but usually containing sweetening, currants, spices, etc
any of various types of small round sweet cakes
a hairstyle in which long hair is gathered into a bun shape at the back of the head
(slang) have a bun in the oven, to be pregnant
n.

A state of drunkenness; alcoholic exhilaration: A bun is a light jag (1900+)
The buttocks; bum •Originally ”the tail of a hare, scut”; first seen applied to persons in Scottish poetry (1530s+)
A single buttock; cheek: a boil on my left bun (1970s+)

blood urea nitrogen