I will leave this for some of the younger contributors to comment on - personally I have no idea what Booyah! means (is it an English word??), nor what it is you are going to have, or what you are going to get into - but I shall read the other responses with interest and may learn something! Enjoy your holiday. Oh, and it is 'holidays are coming'.

I agree with Peter - talk to your native-English-speaking friends who will be at the party. If you really want to use any phrases, make sure you're absolutely comfortable with them. Let's look at this another way: if I pre-learnt slangy Spanish phrases for a party in Spain and shouted them out robotically in my Australian accent, I'm sure you couldn't help laughing at me. I'd just sound comical. ;)

Hmmm....I would be wary of trying to "pre-learn" expressions which change so frequently and which are often peculiar to particular age, gender, social and national groups in English speaking countries. It so easy to embarrass yourself by the wrong choice of colloquial expressions. The best advice is to listen to the expressions your English speaking friends use and then when you think you know the context of their use, try them out yourself. Ask your friends if what you have said is acceptable. None of the expressions except for "brilliant are familiar to me - some of them sound quite odd. Even "brilliant" is overused and stale.