At the end of every episode of Yuru Yuri San Hai! (third season of Yuru Yuri), there is a cross-review section (right before the preview of next episode) which features an item used in the main section of the episode. For example, the shirt that Toshinou Kyouko bought that says I am AHO (AHO is Japanese, means stupid).
I can find that shirt being sold in the Internet, though I'm not sure which one comes first, the shirt or the anime. This makes me curious, are the items featured in the cross-review section are actually based on real world items, or this t-shirt is just a coincidence? By coincidence, I mean it just happen to be famous and thus was created or the shirt got featured because when the series creator browse the Internet for idea he/she thought that it is funny.