"
>> Q1: Last Sunday for dinner we had...?

Rotisserie beef roast

..
>
>> Q2: The last time we had that for dinner was...?

Maybe six weeks ago

>> Q3: Last grocery shopping trip forgotten item...?

Sour cream. I have a method that works fairly well. I know that I have to
pick up a certain number of items. I make sure I have that number of items
when I'm heading to the checkout. Sometimes I see something that looks good
and grab it and leave out one of the required items.