What to do for our 4 year anniversary?

My boyfriend and I will be celebrating our 4 year anniversary in October this year. We want to do something like Six Flags or something fun, maybe stay over a night or two in a hotel or lodge. I don't know what else to do. He said that we should do something real big every 5 years...so this year is only 4, but we still want to go do a weekend getaway since it lands on a Friday. We're located in Sullivan County, but we like going to NJ or PA or upstate NY near Lake George and whatnot. We've already done many romantic things like going out to a fancy restaurant, home made meals with candlelight, warm mages, etc etc etc.....we want to actually have a FUN "WAHOOO" time, can still be romantic, but we want to have a lot of fun and laughs.... Any suggestions? (Please, no harsh remarks that are unnecessary or irrelevant.) Thanks to all who respond respectfully!!