Khapee is just saying "happy" in a typical Pashto accent. Khappay is a Sindhi word...means 'needed'. You're right happy...its somehow related to Mr. President Zardari. He said "Pakistan Khappay" after his wife was assassinated.

btw...I am learning proper Arabic through Fanar. Still in the basic level where they teach us the Arabic alphabets and its correct pronunciation...Though, I already know it but still worth of it.