For those people who have experienced a momentary lapse of reason or a forgetful "tip of the tongue" moment, there is a very accurate — if inelegant — term: a brain fart. This can either be an ill-advised moment when a person temporarily forgets his or her circumstances before speaking, or it could be a so-called "senior moment" when a familiar thought or piece of common knowledge cannot be recalled instantly. A driver may have one on a highway, for instance, and drive right past a familiar exit ramp.
Many people experience this type of lapse whenever they temporarily lose mental focus or concentration on the matter at hand. While in that unfocused moment, an employee might forget he or she is speaking to his or her boss, or an experienced technician may forget the name of a basic part or tool. Sometimes, a person can overcome the event and continue the task at hand, but other times he or she may have to deal with the consequences before life can return to normal.
The term brain fart is relatively new in the popular vernacular, but the sudden release of bodily gases known as a fart is not. Some sources believe the descriptive but somewhat scatological term is the mental equivalent of a bout of intestinal flatulence. In the same way that the body occasionally emits an unwelcome burst of gas, the brain may create an unfortunately timed bubble of forgetfulness or unfiltered thought. This uncontrollable thought bubble may be temporarily offensive or embarrassing, but it should dissipate as quickly as it formed.
Others suggest that the term is a crude corruption of the medical term infarction, referring to a sudden burst of blood vessels that can lead to strokes or other serious impairments. Suffering an actual brain infarction might trigger the same short-term memory loss or inappropriate outbursts.
Whether it is called a brain fart, a senior moment, or the even more dubious "CRS disease," a temporarily loss of short-term memory or an occasional impromptu outburst is perfectly natural and understandable. Very few people can get through their entire day without experiencing at least one moment of forgetfulness, so it is generally acceptable in an informal setting to apologize profusely and move on.