Despite absolutely no credible evidence that subliminal advertising is effective or exists, it’s a popular belief that it does exist and is effective. (Please note – This doesn’t mean that sex doesn’t sell. It’s just not subliminal.) Here’s link with examples of claims of subliminal advertising:
The most famous claim of subliminal messaging was the James Vicary popcorn message study that was a complete fabrication.
And finally, Saturday Night Live’s Mr. Subliminal: