how yer dern
How yer dern is a variation of "her yer dern". Which in English is actually the question "how are you doing?" This is in reference to the character of Madea as played by comedian Tyler Perry and her unique way of speaking. She tends to accentuate her R's and T's to words that do not need them.
Hellur! How yer dern? Praise da lort it's Friday!