I ordered a chicken and an egg from Amazon. I'll let you know.

Behind the Groan

A Delivery Test for an Old Question

The line borrows the familiar question of which came first, the chicken or the egg, then treats it like a delivery-order problem. “I'll let you know” quietly promises an answer when the packages arrive, without explaining the old debate. Deliver the first sentence as ordinary shopping news and pause before the second. That small delay gives listeners time to recognize both items before the hidden question clicks. No extra explanation is needed once the order is placed.