abbrivation for ( wah de mudda arse?!) aka what the mother's arse?! . an expression of shock and perplexity due to a seemingly unexplainable error or occurrence especially when perpetrated by others.
i saw my best friend with a very ugly girl... i just had to say ,wdma. WDMA?!
facebook keeps mistaking my incessant need to add friends for a spam-bot ... every time i am asked to enter a verification code i always say.'' wah de mudda arse?!''