Rose led fans in a rousing chorus to mark Ashba's 40th birthday while the band was on stage at The Joint venue at the Hard Rock Hotel in Las Vegas, where they have a mini-residency.
Venue staff also presented Ashba with a personalised three-tiered cake decorated with guitars, roses, and a top hat, his signature accessory.
He posted a photograph of the sweet treat on his Twitter.com page, writing, "Holy F**k! Thank you to all of the fans around the world for making this the best bday (birthday) so far!... Thank you so F'n (f**king) much to hardrockhotellv TheJointLv (sic) for this insane bday (birthday) cake! I will never forget this!"