The classic party game in which one player is blindfolded, and tries to find one of the others, who are moving about, and sometimes has to guess who they have found by feel, or hearing them speak in a disguised voice. The game is often referenced in old fiction, as something children would do for a bit of impromptu fun. "Let's play blind man's buff while we wait for supper!"
I think it's become a forgotten game, in this age of safety, or people think of it as belonging to the era of Charles Dickens. When I was recently discussing party games with some people in their thirties, none of them had heard of it. It's probably been banned from playgrounds, like conkers, and British Bulldog.
Did you ever play it? I don't think I did as a child, but I remember playing it as a teenager once, abroad on a school trip, while we had a dull moment outside in the cold, and this was to the bemusement of passing tourists.
YANBU - I played it
YABU - I never played it