Your selling idea should be an irresistible expression of why your prospect ought to buy your product. Your idea shouldn't shock as much as surprise. An insult gets someone's attention but doesn't predispose her to your sales message. So please don't bring in pictures of toilets to sell food. Assume your first thoughts have been done.
Creative people have a natural hankering dig deeper.
When you get to your 15th or 20th thought you're probably getting original. And believe working copywriters when they tell you puns don't sell. Puns get in the way of a selling idea by calling attention to themselves instead of what you're selling. Your work doesn't have to be beautifully rendered on a computer. A simple drawing of your idea will do.