This was a great fundraiser at our church. It was lots of fun and raised a nice amount of cash.
We marched in during Sunday Service and took our preacher hostage! (We'd had a word beforehand and arranged for the associate pastor to do the sermon that week so he was ready to jump in!)
We ended up raising a lot of money from the congregation to get their "pastor out of jail". It was very comical. We used it to raise money for the youth camp.
You could make this even funnier by having the preacher tied and gagged outside the church waiting for the congregation to exit. An extra chance to rattle a fundraising bucket also!