01 Adapted from Ries, E. (2011). The lean startup: How Today's Entrepreneurs Use Continuous Innovation to Create Radically Successful Businesses. Crown Books.
02 See Wheeler, E. (1938). Tested Sentences That Sell. Prentice-Hall.
03 Another version compares “sausage” to “sizzle.” You can’t sell a sausage by describing it – “a cleaned-out animal intestine filled with unsellable waste meat” is accurate but unappetizing. You have to sell it with the sizzling sound of “zzzzzsh.”
04 A great card set (in German) for ideating advertisements is Klell, C., & Pricken, M. (2005). Kribbeln im Kopf: Creative Sessions. Schmidt. It is based on the book Pricken, M. (2008). Creative Advertising: Ideas and Techniques from the World's Best Campaigns. Thames & Hudson. Also see Using cards and checklists in #TiSDD 6.4, Ideation methods.
05 Goldenberg, J., Mazursky, D., & Solomon, S. (1999). “The Fundamental Templates of Quality Ads.” Marketing Science, 18(3), 333-351.
Developing service advertisements as prototypes can help you quickly explore and capture potential core value propositions that are inherent in a design concept. In the design team, creating a service advertisement can also help the team to (re)focus on the core value proposition of a prototype or idea. Later, they can be used to test if the target audience understands and values the innovation.
The most widely adopted form for a service ad is the simple advertisement poster (or ad poster) – a fairly big A1 or A0 poster that uses concise slogans, engaging visuals, and text to communicate or sell in public places like bus stops or your favorite shopping street. Further into the project, service advertisements can also be created as online ads, web landing pages, or TV or video advertisements – including in-depth documentary-style variants.
When taken to a wider audience for test and research, service advertisements have proven to be very effective in implementing a “fake it before you make it”-approach to prototyping. Online shoe retailer Zappos did not start by prototyping expensive and complex distribution or warehousing systems. Instead, the founder created a prototype which focused on exploring and evaluating the core value proposition: will customers be willing to actually buy shoes online? He set up a lightweight web shop to sell shoes. Anytime someone ordered a pair, he would pop over to one of the local stores, buy them at full price, and mail them. Thankfully, he discovered that there actually was a demand. In 2008, Zappos hit $ 1 billion in annual sales, and it was sold to Amazon in 2009 for $ 1.2 billion. 
Effectively, many campaigns on crowdfunding platforms can also be seen as advertisement prototypes trying to sell a) the service or product and b) trust in the team that they will be able to implement when the funding campaign is successful.
When creating an advertisement prototype, it can be useful to remember Elmer Wheeler’s famous quote: “Don’t sell the steak, sell the sizzle. It’s the sizzle that sells the steak and not the cow. Hidden in everything you sell in life is a sizzle. The sizzle is the tang in the cheese, the crunch in the cracker, the whiff in the coffee and the pucker in the pickle.”  This implies that you need to go beyond simply describing the facts about your new product. Take a family car, for example. It might be nice to know (for some) that it features a steel cage made from hot-formed boron steel (“steak”). But what matters more: this thing (“boro …WHAT?”) keeps your family safe (“sizzle”). On the other hand, only talking about the benefits – the sizzle – won’t work either. Nobody will buy “a mystery product that will make you rich” without knowing at least roughly what they are buying.
For prototyping purposes, it is key to go for a balance. Your service advertisement needs to explain enough facts and details (“steak”) that the audience can understand what the new service or product actually is, but it also needs to convey enough emotion (“sizzle”) that they can also understand why they should care. With this combination, there is a good chance of valuable feedback from your research audience.