I thought it would be funny if the coupon itself was expired. It reminds me of a great joke in an old Mad Magazine. The author said he left a dollar on the page for the kid and hoped his mother didn't find the magazine and take it for herself. The was a small smudge to make it look like old glue was there. Hey! I misspelled "value."
(So. . . you would need a second coupon-coupon to use this expired one.)