Have one in the oven phrase informal
if a woman has one in the oven, she is pregnant.
She quit coffee when she had one in the oven.
My wife is having a bun in the oven, and this is our first child.
Used to say that someone is pregnant
The verb "have" must be conjugated according to its tense.
Used to describe someone who is naive, gullible, inexperienced, easily fooled, ignorant, unsophisticated, etc.
You don't even know this simple thing? Have you just fell off the turnip truck?