It does not matter that “Viagra” is one of the most searched terms on the Internet if you sell baby blankets online. Only use and include keywords that are specifically relevant to the product or services that you are advertising. If you do not, your ad will not be approved, nor will you draw natural traffic if the search engines see you using keywords that are not relevant to your product offering. All web traffic is not good traffic anyway. Don't waste money for all those clicks by users looking for something other that what you have to offer!