A British clergyman struggled along with a small congregation in a small neighborhood. A commercial firm offered to supply free hymn books, provided they could insert a bit of discreet advertising into the hymnals. The pastor was reluctant but finally agreed. When the hymnals arrived, he eagerly examined them and was delighted to find no brash advertisements on or inside the covers. 

The next Sunday, his flock began to sing from the hymnals. All went well until the third song, in which the congregation lifted their voices in unison to the melodious notes of:

Hark the herald angels sing,
Hanson's pills are just the thing;
Peace on earth and mercy mild,
Two for men and one for child.