Uh-oh, Slayer's "Angel of Death" and Wham!'s "Last Christmas" have been Frankenstein'd together for a holiday season mash-up.

For sure, listeners would be hard-pressed to find a more rhythmically impressive mash-up than this concoction. Largely, the vocals from the thrash metal group's 1986 Reign in Blood opener "Angel of Death" have been meticulously fused with the ubiquitous Christmas tune from the late George Michael's boy band duo.

But that doesn't make the combination any less jarring — if not altogether nightmare-inducing. The tune is just the music from "Last Christmas" with Slayer singer Tom Araya's "Angel of Death" lyrics layered on top. Not until around two-thirds of the way through does a chugging metal guitar enter the unlikely sonic scene.

By the end of the mash-up, the familiar "Last Christmas" refrain finally shows up. Listeners have musician Andy Rehfeldt and editor Tony Colella to thank for the musical mixture shared to YouTube last week (Dec. 11).

"The music was performed and recorded by me, and the vocals were found here," Rehfeldt writes in the description. Those wishing to encourage the musician further can visit his Patreon webpage.

The mash-up isn't the first time Slayer's "Angel of Death" has experienced a surprising workaround. In 2014, the cut got a blistering banjo cover. A year earlier, a 12-year-old drummed along to the metal song.

Perhaps unsurprising was that Slayer used the tune as their final song to say farewell at their last-ever Los Angeles concert last month. Anyway, Listen to the Christmastime mash-up, along with both originals, below.

Slayer "Angel of Death" + Wham! "Last Christmas" Mash-Up

Slayer, "Angel of Death"

Wham!, "Last Christmas" (Official Music Video)

Slayer Songs Ranked