Unenthusiastic Surprise Party Response

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

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

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