Is Google AdSense starting to work?

I just noticed today that instead of an ad to join Blogger, the ad on my blog now is for breakfast recipes.  Since most of what I've been writing about has mentioned food in some capacity, maybe this means that the targeted ads are starting to get implemented.  I wonder if this is also a sign that I should focus on writing food-related posts, in order to create some sort of crazy positive feedback where the ads will get bigger and more delicious.  I'm also curious as to whether I could deliberately change that by inserting specific words in each of my posts out of context, and if so, how frequently would I have to do it. . .

Maybe I should start typing "walrus" in my posts at "walrus" random "walrus" times.  I can see "walrus" this losing "walrus" its "walrus" novelty really quick.  "walrus" "walrus" "duck" "walrus"