For the second time in the past month, Green Day's Billie Joe Armstrong got to play guitar with one of his favorite bands, Minneapolis legends the Replacements. He donned a guitar and a suit for a set with the band during this past weekend's Shaky Knees festival in Atlanta.

This comes after Armstrong joined the band as an "expansion," as Replacements frontman Paul Westerberg called him, during the band's Coachella performance last month. According to the band, he was helping to fill out the guitars while Westerberg sang from a couch due to back problems. Here's a clip:

An event needs to occur at least three times for a pattern to develop, so the Green Day frontman has to show up onstage with the Minneapolis rockers at least one more time before we can begin speculating with any sense of credibility.

Until then, everyone is watching with baited breath to see if Armstrong is going to be a permanent member of the Replacements. After all, if Tommy Stinson can be a member of Guns 'N Roses, anything is possible.