Have you ever wondered why a pair of trousers (or 'pants' if you are either American or John Gray) is referred to in the plural when it is in one piece? "Fetch me my pair of trousers Geeves." "Yes Sir, I will fetch them immediately."
Well, the first trousers were just two legs - a left and a right one. This left the man's bits and pieces exposed to the elements, and woollen undergarments did not stop a strong East wind, so a seperate, strap-on (no, not one of those) piece was made that covered the gap between the two legs. I once tried to make a pair of trousers from a pattern, but just could not get then into one item, despite detailed instructions.
This joke is pants.
Q: What has four legs and flies?
A: Two pairs of trousers.
(Image courtesy of Lucy Worseley - the dirty bitch!)