Clapping One's Hands and Whistling
Question :
What is the ruling on people whistling and clapping their hands in parties?
Answer:
This practice appears to be taken from non-Muslims; therefore, it is not an appropriate thing for a Muslim to do. When a Muslim is joyful about something, he says 'Allahuakbar (Allah is the greatest)', or 'Subhanallah (How perfect Allâh is!)'.
Furthermore, it is incorrect to say "Allahuakbar in unison with a group, as some people do. A person should say this by himself; there is no basis to saying so in unison with others.
Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 8 Page 125