an ounce of sense

Used primarily in negative constructions.

1. A tiny or fundamental amount of sound, practical judgment, understanding, or intelligence. Used after "have." Jimmy almost crossed the street without looking up from his cell phone. That boy doesn't have an ounce of sense! Does Barry have an ounce of sense? Why would he tell his parents in advance that he's planning on sneaking out to go to the party? Shirley would rather spend a day and a half riding a train there, instead of just taking a three-hour flight? Wow, she doesn't have an ounce of sense, does she?

2. A modicum of meaning or coherency. Used after "make." The movie's action scenes were very exciting, but its plot didn't make an ounce of sense. Can you make an ounce of sense out of these strange markings? Is it some sort of code? Math has never made an ounce of sense to me. It feels like I'm looking at a foreign language!