['I have a big surprise party planned for my friend tonight.', "You sound like a good friend, going through the effort and trouble to fix that up. I'm not into surprises, but I'm sure you know your friend well enough to know that he'd like it if you gave him one.", 'Yeah I just wanted to show him that we are thinking of him and that he is a very special person.']
It's going to be really easy to see that he is special to you guys after tonight. I wish I had a friend like you, even though I don't like surprises. You should be proud of yourself. I hope it goes smoothly!
It is my friends birthday today.  I have put together a surprise party for him tonight.