Many singers have trouble with certain sounds, and I think Hank must have had trouble with the sound "-eer" or "-ear". In "Bucket" he sings "I can't buy no bee-yar", and in "Crazy Heart", he sings "You thought she kee-ared for you, and so you acted smart...". Another explanation for his weird pronunciation of "beer" might be that by the late 'forties, country music was between it's rough-and-ready past ("I Wish I'd Got Me a Half a Pint, and Stayed in the Wagon Yard"), and its honky-tonk future, and in an effort to keep it respectable, the producer didn't want the listener to quite understand the word "beer". (A little far-fetched, that.) Or maybe Hank just liked the way it sounded.