As to calzon chino -- I can't explain why the spaniards came up with it, but traditional Japanese underpants are pretty wedgieful (https://jref.com/articles/fundoshi-japan...cloths.65/) I wouldn't be surprised if China were similar.
As to techniques - I was around in the early wedgie days of Internet 1.0 (World Wide Wedgie forum, Yahoo groups, etc.) and remember discovering how absolutely brutal the propeller wedgie was - remember submitting it to the internet and watching it "take off" :p. Meetups are easier and more common these days, but the pre-smartphone, old technique lists were lonelier internet wedgie nerds trying to get new, different ways of getting their undies up their butt.