How does one successfully throw a surprise party for a heavily armed paranoid schizophrenic?

Spike the punch with Clozapine and convince him the guests are only his usual shadow people.

Answer the door with a semi-auto pistol and have everyone in the room pointing guns at the door as well. Then when the guest comes in shine a large spot light on him/her and then yell 'Surprise!'. Also be sure to spike the punch with horse tranquilizers to add that extra special element to the party. :)

I would say he would know. But my family and I celebrate his birthday on April 6 , and what we will sacrifice for the year for him . We have a cake ice cream and write down what we would be willing to do and read it allow. Christmas is for what he gives to us. This is not my religions belief its just something that we do because we know he was really born in the spring time and for fun.

From a distance.

Perhaps someone's moochy cousin or other disliked relative could be persuaded to be the one to open the door and yell "Surprise"?

put on a mask, and just jump out from a Corner screaming what is supposed to be "surprise", but as if speaking in some otherworldly language (meaning either 'demonic', or 'alien'), flailing your limbs about wildly.

then...off to youtube with it.

Dress everyone in leotards and call it the Battle of the Bulge.

Extra cake.

heavily armed? Or hairily armed?

Did I say that?

Yell surprise roll and duke..

Have everyone dress up in medieval armor or that shark-proof mesh...