Vaginal flatulence is the expulsion of trapped air from the vagina that usually occurs during or immediately after sexual intercourse. Although air expelled from the vagina is usually odorless and does not contain waste gases like methane, the sound of a flatus vaginalis is similar to that of anal flatulence. A common slang term for vaginal flatulence, "queef," probably describes this sound in an onomatopoeic fashion. In most cases, expelling air from the vagina is normal and not a cause for concern, although many women find the sound embarrassing, particularly if it occurs during intercourse. There are some cases in which vaginal flatulence may indicate a more serious medical condition, however, such as a rectovaginal fistula or female genital prolapse.

During sexual intercourse, the movement of the penis in and out of the vagina forces air to become trapped inside the vaginal canal. This air must then be expelled, in the form of a flatus vaginalis. Penetration of the vagina is the most common cause of vaginal flatulence, but it may also be caused by other forms of sexual contact, such as manual or oral stimulation, or even by intense exercise or stretching. Forcing air into the vaginal canal on purpose can be potentially dangerous, as it can lead to a condition called an air embolism, in which air bubbles are forced into the bloodstream.

Although expelling air trapped in the vagina is often normal, many women find the noise it makes embarrassing and attempt to find methods to stop it from happening. A common method for reducing instances of vaginal flatulence is to strengthen the vaginal walls and pelvic floor by performing Kegel exercises, or simply Kegels. Kegel exercises involve the contraction and relaxation of the pubococcygeus muscles that stretch from the tailbone, or coccyx, to the pubic bone. Strengthening these muscles in the pelvis causes the vagina to clench more tightly during intercourse, forming a more complete seal that does not allow as much air to enter the vagina. Using a sexual lubricant may also help to reduce vaginal flatulence.

Since vaginal flatulence is usually only composed of air, a flatus vaginalis that has a foul odor may indicate a condition called a rectovaginal fistula. A fistula is a passageway that forms between organs or vessels in the body that are usually not connected to one another, such as the rectum and the vagina. Rectovaginal fistulas may form as a complication of pregnancy or surgery, or their formation may be connected to an infection. They can cause incontinence and infections of the vagina and urinary tract. Another condition that is linked to vaginal flatulence is a complication of childbirth known as female genital prolapse, which causes the vaginal canal to fall out of its normal place.