Both of these are currently hanging up in my kitchen. Probably the only thing I'm going to miss about living in Chapin is the appearance of mysterious messages on a daily basis. At this point, this is the closest I get to communicating with my roommates.
The best part of this one is that we don't actually have a trash can anymore. In response to a few ants crawling around the kitchen, one of my roommates threw away the trash can and posted this note. Apparently putting all your food in plastic bags on the floor is a good way to deter a giant ant infestation.
I've heard from quite a few reputable sources that unplugging a rice cooker that hasn't been turned on for weeks can have disastrous consequences. Two of my roommates are engineering students which may or may not explain this diagram.
At least these weren't written on the refrigerator.