A bulge or wrinkle in the seam of a skirt that look similar to the bulge in a mans pants. Often caused by the misplacement of a dart or seam when sewing.
Mad Seamie is something you say when somebody does something completely mad or idiotic. You also use it sarcasticly when a person never does anything without thinking about it first.
If a person does a totally madact you call him 'Mad Seamie' from then on.