AHAA (Pronounced A heavy h a) originally means I do truly object - إني حقا أعترض

It's an objection statement, still used as one in the current Egyptian slang but with a twist ;) The same way you use "Are you kidding me/WTF/Shit" to express excitement or objection. 

It dates back to around the 1100's. A time where the Egyptians used it to protest the socio-economic situation. The regime banned the use of the word at the time and somehow it lost its true meaning as it became a no no word for the Aristocrats and elite in Egypt.