Pregnant. The idiom bun in the oven refers to pregnancy. The “bun” is the baby, and the “oven” is the mother's womb. Perhaps it alludes to the warmth and shelter the mother's womb provides.
Teacher: "Kids, I have a Bun in the Oven"
Kids: "YAY, I WANT A BUN! GIMME"
Teacher: "I'm Pregnant."
Kids: "AW I WANTED BUNS!"
by The Internet Is Porn December 19, 2019
when a gurl is prengant.
"yeah, my gurl got a bun on the oven-just found out last week."
by 'lil keep' August 12, 2005
When someone is pregnant, typically with more than one child when "buns" is plural. See also bun in the oven.
Person 1: Hey, isn't your wife pregnant?
Person 2: Hell yeah! This bitch has got buns in the oven!
by mehtyn February 28, 2018
For a woman to be pregnant
Any illegal immigrant woman carrying a bun in the oven who comes to the United States solely to give birth to an anchor baby, well her offspring shouldn't receive automatic birthright citizenship.
by Sexydimma December 1, 2015
Similar to a Dutch Oven, in which one farts under the bed covers and traps a person underneath said covers, forcing them to sniff your vile ass fumes.

With a Dutch Bun in the Oven, you actually have a length of turd hanging out of your asshole, thereby adding potency and immediacy to the oven.

A Dutch Oven shart.
I almost made my girl puke this morning when I trapped her under the covers and sharted out half a turd, screaming DUTCH BUN IN THE OVEN!!!
by mbossss October 19, 2010