If you are simply going to have to make up an excuse to get out of it, just don't go. Have you ever actually heard of anyone getting arrested for not showing up for jury duty?
If you are thinking about lying, take a look at the following article:http://www.unknownnews.net/0605-1.html
I don't know about your state, but some allow you to simply call the jury coordinator and say "hey...I can't do it right now..." and have it rescheduled for like 6 months down the road.
There are things that will likely keep you off a jury. None of them are very pretty. Racism, sexism, bigotry, felony conviction, belief that the cops wouldn't have arrested him if he wasn't guilty. If I really wanted to get out of jury duty, I would find either a t-shirt with swastika, KKK logo, or the logo of my favorite strip club (preferably with offensive pictures and messages).