Based on the derivative word turkey, 'turkah' is used to as a slang pronunciation of the word. Imagine you're Mr. Garrison from South Park, and say the word Turkey out loud. Bam, there you have it. . . turkahh!!!
Turkah was originally created to fit into a riddle with the words Erca, Durkah, Burka, and Workah.
"Hey Erica, pass me that god damn delicious turkah. . . I'm gonna slop some greasy gravy all over that succulant bitch, it's such a plump and juicy looking turkah!"