[Terr_]

The ambiguity of such questions drove me up the wall as a child.

My mother has a story about how I would ask about future events as "the day after the day after the day after the day after the day after today", which in my mind was much clearer than "in X days" why it wasn't clear how rounding occurred.

Clearly, this set me up for a career involving off-by-one errors.

[MrMcCall]

Ha! That's truly funny and obeys some kind of comedy rule about taking the story one way and then veering in a different direction. Well done, indeed.

Our daughter used to say "yesterday's yesterday" when she was 4ish and I really liked it.

[haraball]

Norwegian has the phrases "fra og med" and "til og med", where the "og med" means "including". So "from and including Monday" removes the ambiguity.