Grohl's expressions are pretty funny.

As one would expect Foo Fighters to do when their tour reached Canada, they paid tribute to the Great White North’s favorite band by covering a Rush song in Edmonton, Alberta last night (Aug. 12). But rather than have Dave Grohl or drummer Taylor Hawkins sing “Tom Sawyer,” they called up a fan named Brian to handle Geddy Lee‘s vocals.
“Welcome to my nightmare,” Grohl says, after warning him to not “f— it up.” He then handed Brian the microphone, and Brian didn’t disappoint. As you can see in the video above, he handled the high notes about as well as anybody could, and Grohl’s expressions on the video screen show that he was impressed.
“Dude! That was f—ing amazing,” Grohl said after the song. “Holy s—! I don’t even know — what the f—? What was that? Dude, are you a eunuch? How did you f—ing hit those notes?”
That the members of Foo Fighters are Rush fans is no big secret. After all, Grohl inducted them into the Rock and Roll Hall of Fame two years ago, with he and Hawkins performing “2112? with them at the ceremony. Grohl later said that Neil Peart was “as influential as any religion or any hero or any person in someone’s life,” and that he cried after they first met.
Foo Fighters resumed their North American tour with last night’s show, with Grohl still seated in the throne he designed after breaking his leg when he fell off the stage on June 12. They will remain on the road for the next two months, when the tour concludes in Castaic, Calif., on Oct. 18.