The Google slap is a term which applies to advertisers who are using adwords but in a way tht G thinks is spammy and they will penalize the ad. That was the original meaning of the SLAP. it has a popular term to describe anything that Google penalizes a site for but its really referring to advertisers.
In the case of advertising, a Google slap can mean a couple of things:
1. Google sees the ad and its landing pages as poor quality. It will significantly lower the ad’s position in search results.
2. Google sees the ad and landing pages as so poor in quality that it will disable the associated AdWords account.
Not a good scenarios for any advertiser
This article helps you avoid a slap for advertising and its good strategy fpr SEO also.
Read more at http://www.searchenginejournal.com/how-to-avoid-being-google-slapped/22703/#jw4bxrgk1cZTShT1.99