Most likely the younger sister of a skank, a mudguts typically has at least two inches of stomach showing. To be a true mudguts the stomach must also fall two inches beyond the top of her short skirt. A beer gut for young women. Muddy for short. Example: For a sixteen year old she must drink a lot of beer. She isn't pregnant, so she must be a mudguts.
MUDGUTS
Meaning of MUDGUTS in English
Slang English vocab. Английский сленговый словарь. 2012