Hermione was going skiing with her parents, something that greatly amused Ron, who had never before heard of Muggles strapping narrow strips of wood to their feet to slide down mountains.
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There has definitely been 'switch 2, 3 swap pretz 2' but think about how difficult front '3 swap pretz 2' is compared to 'blind 3 swap pretz 2'. getting that pretz 2 after spinning 630 in total would be very hard.
I wouldn't be surprised if this has never happened before in skiing