They've been playing this song on the radio:

I drink the Shiner and the Pearl, sing the Waylon and the Merle
We pick a little "Ramblin' Man"
Pounding out the rhythm in this five-piece honky-tonk band

I couldn't resist a minor modification:

I drink the Shiner and the Pearl, eat the possum and the squirrel
On Sundays we have barbecued skunk
We couldn't stand to eat that if we wasn't shiftless and drunk

"Squirrel", of course, is pronounced "squirl", to rhyme with the four basic ingredients of an oil patch Friday night: you find some girl, drink some Pearl, listen to Merle, and, eventually, hurl.