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When you go to google adwords site, and enter "internet humour" into the keyword search box, you find for "advertiser competition/search volume" the following:
Internet Humor: 60% / 25%
Internet Humour: 0 / 25%
So people are search about as often for both phrases, but only advertising for the Humor version
...snip...
Now about the automatic SEO: Nothing is automatic, although yes, having these keywords for the domain is a tremendous help in getting good search engine placement. If you mess up the rest of the page with unrelated keywords lowering the density you may have problems.