Basically Day wanted the veto because she doesn't trust Tiffany even though Tiffany said she would be safe and Day asked her does she have an idea of who to go up and Tiffany said no so Day just left the have not room and Tiffany said she's putting her up because Day knew she won Roadkill and she'd be safe. But Frank basically wanted Day up so that is pretty much how she got up. Its Day vs Tiff and essentially Frank is working to get votes to keep Tiffany but if people are smart they'd vote out Tiffany because of the simple fact "Why would Frank try so hard to keep her?"
