Brettany is absolutely wearing a diaper in that picture, there's only one thing that can make a crotch that lumpy. Having never seen an adult wearing a diaper under a pair of short-shorts, I feel it is a reasonable conclusion.
Can't make out the t-shirt graphic and don't really care, looks innocuous to me (in a day or two someone will figure out it's an ABDL con or something, I'm sure).
edit: wonder what it takes to get blacklisted amongst furry convention organizers, I know the bar is completely arbitrary but Ravioli is someone whose primary goal in life is to alienate every single person he comes into contact with.