Sometimes at work I get little phrases in my head. They are often unorthodox enough that I have to stop and write them down. It's like in Ocarina of Time, where Navi will go "HEY!"
(interesting fact: the phrase "HEY! LISTEN!" is actually a memetic mutation. It was never a unified phrase—but if you were fast enough on that Up C button—and you had to be if you didn't want to hear another "HEY!" in three minutes—it sure sounded like it.)
Either way, I do stop and "LISTEN!" to the phrase that pops up in my head when it happens.
The final product, when I get home, usually takes the form of verse.