these are called Harvard Sentences. https://www.cs.columbia.edu/~hgs/audio/harvard.htmlFire dept conducting radio tests. The units transmit on the repeaters, then on simplex, with what appears to be a random sentence. Dispatch replies and quotes the sentence. Dispatch usually quotes it accurately.
Unit: On the mobile repeater, the colt reared and threw the tall rider.
Dispatch: Roger, the cold rear, uh, something, copied you 5x5.