A: Have you made up your mind on where to go for the Christmas vacation?

B: Not really. I want to spend a couple of peaceful days on the beach, but John wants something more exciting.

A: My advice: Don’t try to combine a relaxing vacation with an adventurous one; it would fall between two stools!

Note: This idiom, first cited in the late 1300s, refers to the scenario where one comes between two alternatives and so fails to fulfill either. The image is vivid, as you can picture someone trying to sit between two stools and then falling to the ground.