The "tutorial" mission in Frontierville involves finding a lost sheep and bringing it back, he explained. Because it's a Facebook game, you get the option to post when you've done so, which shares a little blurb about your achievement and a picture of a cartoony character struggling to pull a stubborn sheep. But that's not what players' friends saw.
"What is she doing to that sheep?" was a common refrain from people who saw that post, Reynolds said. "The look on the sheep's face kind of sells it." But this wasn't a problem, as it turned out. That pseudo-scandalous sheep image "has our highest post rate and our highest clickthrough rate," he explained, with many more replies to those posts creating increased visibility, and thus inadvertently promoting Frontierville. And so Zynga went forward with innuendo-laden status messages, more examples of which you can see above.
At the end of the presentation, Reynolds answered a question about his reaction to Satoru Iwata's GDC keynote, during which Iwata pretty clearly denounced social and mobile games in general. "I don't understand why they'd feel threatened," he said, suggesting that social games and console games can coexist. "Maybe that person thinks a lot about console games," but not about mobile games.