Well I remember you asking exactly the same question before - http://forums.digitalpoint.com/showthread.php?t=1241705 so that must prove something.
yea innuendo and flirty ones are pretty catchy, btw what kind of add is it? that way you can get more suggestions
Remember those MySpace ones with the cockroaches running around? You had to ZAP them! Probably to win a FREE XBOX, haha. They definitely were CATCHY.
The best approach to make your advertisement interesting and eye catching is to go by AIDA model. AIDA is the acronym of Attention, Interest, Desire and Action. So when you design you ad, think of attracting attention of your prospective customer. Now attention can only be grabbed thinking with your buyers mind. Ask yourself what would be the thing that can catch your customers attention. For example, you are selling some product, you can come up with such statements as by two, get one free or gift for you. You can also grab attention by using visual effects or use of eye-catching colors or images. It depends what you want to sell or highlight. Rest of elements of AIDA model come after successful designing of first A i.e Attention.
Your ads must be short and having the important information. And you need to do the web 2.0 type of ads so that it will look more attractive.