In the UK, there was one that really sucked.
T'was an ad for some sort of tablet that was designed to soften water in your mashing machine so limescale wouldn't build up and damage it. Fair enough, but why oh why did it have to end with such a cheap 60s jingle?
"Washing machines live longer with Calgon!"
...and with that post, people of Britain were so surprised that "tea was spilled, crumpets were dropped and monocles everywhere popped out in shock."