If there were any doubts that the Foo Fighters are the biggest band in the world right now, Dave Grohl and company put them to rest during their massive surprise gig at the Forum in Los Angeles last night (Jan. 10).

Celebrating Grohl's 46th birthday a few days early, the Foos pulled out all the stops and invited a seemingly never-ending list of friends to join them onstage throughout the night. While the actual Foo Fighters portion of the setlist is what you'd expect ('All My Life,' Learn to Fly,' 'Everlong') the real fun came in the form of several covers -- and not just covers, but covers with very, very special guests.

As they took the stage and jammed for a few minutes, Grohl knew exactly what to say to get the crowd pumped up (as if the sold-out Forum wasn't already pumped up enough): "Just so you all know, it's gonna be a long f--king night ... so let's start this s--t off right, right out of the f--king gate. Would you please welcome my good friend, Paul Stanley from Kiss!" And with that, the Foos tore into their 30-plus song set with two Kiss covers -- 'Detroit Rock City' and 'Do You Love Me.' Check out the beginning of the concert in the video above.

The rest of the show included just as surprising and exciting guests as Stanley, including Slash, Tenacious D, Alice Cooper, Queens of the Stone Age's Nick Oliveri, Zakk Wylde, Perry Farrell, Trombone Shorty, David Lee Roth and Lemmy Kilmister. (You can see the entire setlist below.)

For those fans who were paying attention to the Foo Fighters' official Twitter account last week, some of these guests might not have been big surprises; throughout the past few days, the band tweeted a handful of YouTube videos featuring some of the rockers as a bit of foreshadowing for what was to come.

If you were lucky enough to be at the Forum last night, you witnessed an unforgettable show that will likely put the rest of your 2015 concert-going experience to shame. If you weren't able to make it, thanks to several fans, the night has been captured on camera forever (or until YouTube pulls the videos down). Check out some of our favorite clips below, and get ready for the Foo Fighters' massive worldwide tour set to kick off in Chile on Jan. 15 -- here's to hoping the Forum show is just a taste of what to expect from the Foos' full-blown 'Sonic Highways' tour!

Foo Fighters With Alice Cooper -- 'School's Out'

Foo Fighters With Zakk Wylde -- 'N.I.B.'

Foo Fighters With Perry Farrell -- 'Mountain Song'

Foo Fighters With Slash and Tenacious D -- 'Immigrant Song'

Foo Fighters -- 'Everlong'

Foo Fighters -- Setlist, Jan. 10, 2014
‘Detroit Rock City’ (Kiss Cover, with Paul Stanley)
‘Do You Love Me’ (Kiss Cover, with Paul Stanley)
‘All My Life’
‘The Pretender’
‘My Hero’
‘Tie Your Mother Down’ (Queen cover, with Slash and Tenacious D)
‘Immigrant Song’ (Led Zeppelin cover, with Slash and Tenacious D)
‘School’s Out’ (Alice Cooper cover, with Alice Cooper)
‘I’m Eighteen’ (Alice Cooper cover, with Alice Cooper)
‘Cold Day In the Sun’
‘Monkey Wrench’
‘Two Headed Dog’ (Roky Erickson cover, with Nick Oliveri)
‘Learn to Fly’
‘White Limo’
’N.I.B.’ (Black Sabbath cover, with Zakk Wylde)
‘Fairies Wear Boots’ (Black Sabbath cover, with Zakk Wylde)
‘Times Like These’
‘Mountain Song’ (Jane’s Addiction cover, with Perry Farrell)
‘Miss You’ (Rolling Stones cover, with Perry Farrell)
‘Something From Nothing’
‘This Is a Call’
Jam (with Trombone Shorty)
‘Best of You’
‘Panama’ (Van Halen cover, with David Lee Roth)
‘Ain’t Talking ‘Bout Love’ (Van Halen cover, with David Lee Roth)
‘Let It Rock’ (Chuck Berry cover, with Lemmy Kilmister, Slash and Zakk Wylde)

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