Eddie Vedder and Elvis Costello Cover The Who in St. Louis

Wearing a Who t-shirt, Pearl Jam singer Eddie Vedder popped in on Elvis Costello's Friday night show at the Pageant in St. Louis to jam out on a cover of 'Substitute,' by, go figure, the Who.

Vedder's performance was a surprise drop-in prior to his own show at the Fabulous Fox Theatre that same night. He hung out after 'Substitute' to participate in Costello's ongoing spinning wheel gag, a bit in which audience members get to spin the wheel to help pick the setlist for Costello's show. Vedder's spin landed on 'Pump It Up.'

It was the latest in a series of venue-crashing performances by Vedder, who showed up on Thursday night at the Chicago area bar Murphy's Bleachers in Wrigleyville for open mic night. He sang his Cubs tribute song 'All The Way' and covered Neil Young's 'Rockin' in the Free World,' a longtime Pearl Jam setlist staple.

Vedder had been in town for two Chicago area performances Tuesday and Wednesday prior to singing 'Take Me Out to the Ball Game' on Thursday at the Cubs game with former Cub Jose Cardenal. According to Murphy's co-owner James Murphy, Vedder stopped by the bar after the Cubs game with co-owner Beth Murphy and Ron Santo Jr.

"Beth asked him to play a couple of songs at our open mic ... before getting back on his tour bus last night."

Vedder's solo tour for 'Ukulele Songs' continues on Saturday night with a show in Minneapolis.