Just pondering on the Lengberg underwear some more...
I am curious as to why some people (often re-enactors, or SCA) are so adamant that the bikini-like pants must be a female garment. The argument of "women must have worn pants" doesn't make much sense to me. We know that in many later eras women did not routinely wear pants (or wore crotchless ones), making that argument (at least in its most blanket form) false.
I can certainly understand the argument that "women must have done something at that time of the month" - but why does it have to be pants (a la mens'), and why does wearing something for one's period automatically equate to wearing something for the rest of the month too? This argument seems particularly nonsensical to me when it comes to the mid-1300s and before, when mens' braies were huge baggy things that would not be able to hold any conjectural medieval sanitary pad close against the crotch.
In any case, the argument I've been reading about the Lengberg pants in particular is that they look nothing like the mens' braies seen in 14th C and 15th C manuscript illustrations. True. However, a lot of those illustrations are French or English. Also, may I direct you to a woodcut and a sketch by Albrecht Durer: The Men's Bathhouse (c. 1498) and Self Portrait as an Act (c. 1507). Yes, these are at the very end of the 15th C / very beginning of the 16th C. However, I don't know how precise the Lengberg radiocarbon date of "15th C" is. Also, the images are from the correct country. In any case, they definitively show men wearing bikini-style pants.