In serious cases the partition between the anal passage and the vaginal passage can become compromised and fecal matter can pass into the vagina.
Thus when a queef (or vaginal flatulence) occurs, it smells of fecal matter, quite similar to a fart.
This is the grundle-queef. Named for the common ground.
Woman 1: Oh shit
I just queefed
Woman 2: So?
Woman 2: Oh god, is that a grundle-queef?