This is the most mid-'90s thing that has ever happened.
Gwen Stefani joined her husband Gavin Rossdale on stage at the KROQ Almost Acoustic Christmas show in Los Angeles last night to sing a duet version of his band Bush's biggest hit, "Glycerine." This is a pretty sentimental thing for them, as the two met at the annual concert 17 years ago when No Doubt and Bush were first blowing up in 1995.
Source: youtube.com