The title is horribly bastardized Latin I was taught decades ago which means Where or Where is my Underwear? Can't imagine where this post is going, can you? Long ago I remember reading that you can pack less by only taking a couple pairs of underwear and then cleaning them in the sink as needed.
This seems very stupid to me. How big is your underwear that packing 3-4 fewer will save that much space??? For me this is one thing I always pack enough of if not extra! I use it to fill in shoes and boots to retain their shape in packing. I have used them to fill in breakables to prevent crushing in travel (yeah there is a crazy story about dirty underwear and French customs I'm going to have to share one day).
My friend mentioned that she tried to do this once not thinking about the fact that hotel rooms aren't often kept warm enough to dry out the underwear quick enough so she had to wear wet underwear one day and then dry them with a hair dryer the next.
Yeah, I'll pack fewer shoes or jeans, but never fewer underwear!