Sorry I know it's technically a TAAT but I think it was at least 5 years ago if not longer and I am not even sure if it was MN, it may have been another message board... but..
Does anybody remember a really long thread about a joke OPs inlaws had about people walking up stairs?? Op didn't get it and brought it here. Thread was massive and iirc OP ended up saying it has been explained but refused to elaborate?
Google failed me and I cant see it in classics. I am 99% it was MN, it just popped into my head and I am wondering if I dreamt it.