This fallacy basically states that a person's argument is more than likely to be assumed as false or a lie. Although the argument may be true or valid, that person's claim is mistakenly thought of as an invalid argument. This may be caused by that person having a low credibility when it comes to similar types of claims he or she has made previously, such as a person who has lied about something in the past or someone who was wrong about an argument they made.
My example of this fallacy occurred while I was in high school. One of the girls at my school hit her head somehow and supposedly got amnesia. It turns out that she didn't really have it, but acted as if she did for some odd reason, probably to gain attention from everyone. She later admitted to not having amnesia and said that nothing like that would happen again. But, whenever she says there is something wrong with her, like and illness or an injury for example, people automatically assume she's faking it again even when she really is sick or hurt. Even though she may really be under the weather or in pain, some assume that she is lying about her ailments again.