The cast of MTV's Jersey Shore flew to Florence, Italy, to film the fourth season of the MTV reality show - and it appears that both the castmates and the country survived. Now they're safely Stateside and wrapping up a fifth season in their old stomping grounds of Seaside Heights, N.J. To gear up for tonight's Season 4 premiere (10 p.m. ET/PT), USA TODAY's Cindy Clark and Carly Rotter have prepared a handy primer on the goings-ons of everyone's favorite self-described guidos and guidettes.