It's a tie between all prescription drug ads. They say a doctor who self-prescribes has a fool for a patient. How much more so when the "doctor" has no credentials whatsoever?

A close second is the white terrier eating peanut butter. Geh. I couldn't so much as look at the stuff for close to a year after seeing that ad.

I generally think poorly of commercials that involve blue liquid euphamisms and/or baby backsides.

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And you, to whom adversity has dealt the final blow
With smiling [faces] lyin' to ye' everywhere ye' go
Turn to, and put out all your strength of arm and heart and brain
And like the Mary Ellen Carter, rise again.