"A Carpool Karaoke Christmas," streaming Monday on ... For "Die With A Smile," her most recent collaboration with Bruno Mars, she dons an orange wig like the one she wore in the music video ...

So naturally the reaction amongst fans is very much this: "Christmas Tree" is one of several songs Gaga performed for Carpool ... talked about recording with Bruno Mars while working on LG7 ...

Last year, James Corden departed from The Late Late Show, which meant the end of a segment that had become an institution in the music landscape: “Carpool Karaoke.” Well, surprise: It’s back!