I need birthday advice; would you help me please?

Alright guys, my birthday will be coming up in a few weeks. I’ve already had people asking me what I am going to do for it and whether or not I am going to throw a party. So far, my answer has been “I’m not sure what I’m doing and I really don’t feel like having a party.” And that is actually very true and not an attempt as reverse psychology. If I do anything, I would prefer it to be nice and quiet. However, I think some of my friends are planning on throwing me a surprise party. How can I get it across to them that I don’t want a party without 1.) blatantly admitting that the surprise has been slipped and 2.) looking and sounding like a complete jerk? I do appreciate the fact that they’re willing to put effort like that into helping me celebrate, but it’s just not what I want this year.