The mean for wa da fu is one that has to do with a question. Such as meaning when you say wa da fu is dat in the toilet would mean what the fuck is dat in the toilet. In which u would reply my big turd.
Wa da fu is popping out ur ass....omg dat ding is huge o wait dat mibidi!!! OOOOOOOOO *waves arms up and down*
Working as designed, all fucked up. This is a phrase that (according to my dad) originated in WWII. Used primarily in relation to machinery, now applies to a lot of technical solutions.