Foo Fighters promised fans something different every night on their current tour, but it may be tough for them to top what they had in store last week (June 14). At the Firenze Rocks festival in Florence, Italy, three members of Guns N' Roses -- Axl Rose, Slash and Duff McKagan -- came out to perform "It's So Easy."

Guns N' Roses headlined Firenze Rocks, and the we-were-in-the-neighborhood approach was the same used by Dave Grohl back in November, when he sat in on "Paradise City" with the Gunners in Tulsa.

The two frontmen also shared a throne in recent years. In 2015, Grohl broke his leg when he fell off a stage in Gothenburg, Sweden. Although Foo Fighters canceled the remainder of their European tour, by the time they started the North American leg three weeks later, Grohl had designed a throne, complete with guitar necks shooting out from it, while he was high on painkillers. Grohl lent it to Rose when he broke his foot on the eve of the first dates of the Not in This Lifetime tour a year later.

However, Rose made a few changes to it. He made it "a little more low-key," putting in a different base that blended better with the way their stage was set up. Rose also used it during 12 dates in Europe where he sang with AC/DC.

Grohl recently referenced his accident when, nearly three years to the day, he opened his band's Gothenburg show with somebody dressed as Grohl falling off the stage.