Unenthusiastic Surprise Party Response

We all know and প্রণয় our too-cool-for-you characters. They're বন্ধু with আপনি and প্রণয় you, even though they find it rather hard to প্রদর্শনী it.
So let's say this person has a birthday coming up and his বন্ধু decide to throw him a surprise party. What do আপনি think would be his reaction once they yell SURPRISE!?

I know that he's both happy as well as annoyed that his noisy বন্ধু did this without his consent. And he won't be rude to them, cos that would be..well, rude.

আপনি can give a simple explanation as an answer, অথবা আপনি can write a sample scene. Thanks for your help in advance!