A mouth queef is the sound exuded from an individuals mouth that sounds a lot like a vaginal queef. NOT to be confused with a burp. A mouth queef is without control from the person peforming the mouth queef.
person A: lol he just burped
person B: nah G, that was a mouth queef
When your bro attempts to burp but all that comes out is a pussy little squeak.
Todd: *inhales deeply* "<urp>"
Jake: "Dude, quit trying to burp. All that you're getting is these pussy fuckin mouth queefs..."