"phew" also spelled "whew" is not "fuj"
Phew is used when you are happy that something difficult or dangerous has finished or is not going to happen, or when you are tired or hot:
Phew! I'm so glad I don't have to give that speech.
Phew, it's boiling in here!
Fuj to "yuck" albo "ugh" albo uwielbiane przez dzieci "eeeeeewww"