"Ou3a Yef'a3": Lebanese Slang, literally means "watch out it is going to blow up", metaphorically used by men when a snobbish hot chick passes them and does not pay them any attention.
This expression belongs to street slang and is commonly used by young men to praise a young woman over her heavenly figure. Nowadays, it may be used in a sarcastic context to tell a person indirectly that they have gained some weight.
Sample Conversation:
Person 1 is a young pretty lady walking out of a coffee shop to her car.
Person 2 is a young man with not much to do on his free time riding an old BMW. Follows the young lady to her car and puts his head out the window:
Literal Translation: "What a body, you Lioness!"