William H. Macy looks up from his beer, calls for his Ukulele and leads the cast of Showtime series “Shameless” in a hilarious and ribald Christmas song that doubles as some Shameless promotion… literally.

The show is a knock off of a British television series by the same name. It’s a bittersweet look at working class life in Canaryville, a South Side Chicago neighborhood.

The show premiered this year and was the highest rated series debut in the cable network’s history, which green-lighted it for a second season, airing in January.

No wonder the cast comes together for a little good cheer, a Marlboro red (love the product placement), a drink–whiskey, gin, vodka, bourbon, scotch, anything you’ve got–and a holiday song.

In the series, Macy plays Frank Gallagher, a sour working class stiff and single father of six sassy, high-spirited and independent-minded kids, who pretty much have to work around him to get by.

It’s not blue collar; it’s no collar, according to show co-creator Paul Abbott.

Emmy Rossum is beyond hot as Fiona Gallagher, the eldest of Frank’s kids, who must step in and play mother when necessary to keep the kids in line.

In the video, she shows off her classically trained soprano voice. Macy, incidentally, wrote the music and lyrics. And, you can sing along.

Check it out below.

Footnote: In cast you missed it, or want to see it again, “Shameless: The Complete First Season” is out on DVD and Blu-Ray on Dec. 27 from Warner Home Video. Click the link at left to order.