I was flying from Tulsa to Dallas, when I heard a Bonanza check in on Fort Worth Center: Fort Worth Center Bonanza 1234 WITH YOU

(hate that) at 7,500 bla bla bla.

Center comes on and says squawk 0123. After a while the center asks the Bonanza to squawk altitude.

The next transmission I hear is the craziest thing:

Bonanza 1234 confirm squawk please, he replies yes squawking 7500. Center comes on screaming (with bells going off in the background);

Sir, 7500 is the Hijack code, you need to be squawking the code I gave you. You have the whole nation alarmed.