I thought this was rather humorous:
From www.kottke.org:
A man outfitted his family minivan with high-precision cesium clocks to demonstrate to his kids that they gained 22 nanoseconds of vacation time on their mountain camping trip than they would have at a lower altitude.
I can imagine the conversation going like this:
Kid A: “My vacation was longer than your vacation!”
Kid B: “Nu uh!”
Kid A: “YA hu!” Whips out some fancy chart detailing vacation time
Kid B: “No fair!”