The Hollywood heartthrob is currently in Austin to promote new movie `The Rum Diary` and stunned the crowd at the Continental Club by performing an impromptu set with ZZ Top`s Billy Gibbons. The packed venue - which was reportedly at three times its normal capacity - went crazy for Johnny, who stayed on stage for an impressive 90 minutes. Earlier this year, Johnny joined rock legend Alice Cooper on stage at London`s 100 Club. The `Pirates of the Caribbean` star played guitar on two songs during the `Poison` singer`s intimate gig. Twelve songs into his 75-minute set, Alice announced the arrival of a special guest, "the bluesmaster, Mr Johnny D from Kentucky". He then joined Alice on stage to play rhythm guitar on versions of the classics `I`m Eighteen` and `School`s Out`. Johnny has a history with rock bands as in 1997 he played slide guitar on Oasis song `Fade In-Out` and on Shane MacGowan`s first solo album. He also formed the group P with members of Butthole Surfers, Sex Pistols and Red Hot Chili Peppers, and until 2004 was part-owner of the Los Angeles rock club the Viper Room.