a bun in the oven - the state of being pregnant, like a baby is baking inside yo

the state of being pregnant, like a baby is baking inside you, and you can’t wait for it to be done

My mom is a bun in the oven. She’s been eating ice cream like it’s her job.

She said, 'I’m a bun in the oven, and I’m not going to let you forget it.'

That lady is a bun in the oven. I can hear the baby screaming from inside her.