I’ve always wondered- How long can sperm survive in the mouth?

Honestly I’m just curious as to how long sperm can survive in the mouth since the mouth is warm and moist?

And if the mouth is warm and moist and sperm could maybe survive in it, wouldn’t that mean if a guy had sperm in his mouth for some reason like kissing his girl after he came in her mouth or something and ate a girl out that she could get pregnant?

I guess I’m getting to far into my question- so how long can sperm survive in the mouth?