Stop me if you've heard this one. Two men aged around 50 enter a sushi restaurant. One orders a raincoat, the other a garage. What looks like the beginning of a "Monty Python" sketch is in fact the stuff of a most typical oyaji gyagu (おやじギャグ), or old man's joke/gag. Such jokes normally center around words with similar or identical reading, but with an entirely different meaning. Linguists call these homophones.