I Guess I Never Outgrew Literal Thinking

(We are at the grocery store, in the produce isle)

Mom: Caryn, will you grab a couple of tomatoes?

Caryn stops a moment to think about what Mom means by "a couple." With relief, Caryn remembers the explanation Mom gave her about what "a couple" means. "A couple is two, like a couple of people." 

Caryn puts two tomatoes in a bag, then brings it to Mom.

Mom, looking at the bag in confusion: Dear, do you have any idea how many tomatoes we go through in our family?

Caryn: Doesn't a couple mean two?

Mom: Not always.

Caryn, in frustration: You told me a couple means two...

Caryn hesitates, realizing that her mother's explanation of "a couple" took place over fourteen years ago.

Caryn: Never mind. Exactly how many tomatoes did you want?