A quick lesson in singing Latin

Many singers disagree on how to pronounce o's in Latin.  Should it be oh, aw, or ah?  Our choir has opted for aw.  Taking a bit of liberty with the ah and aw, I've changed the words of "Dona nobis pacem" to "Donna knobby knees punch 'em."  I know, my version has one too many syllables, but it sure helps keep in mind not to sing "Donut nobles patch 'em."