Pearl Jam frontman Eddie Vedder once again joined Queens of the Stone Age for their cowbell-driven hit 'Little Sister,' this time at the Chilean outing of Lollapalooza.

It's rare that you get to see your two favorite bands on a tour date together, but it's even more rare that you get to see them perform together. That was the case for me when both Queens of the Stone Age and Pearl Jam played Alpine Valley, Wisconsin for PJ20. A multitude of guests joined PJ on stage throughout the weekend, of whom Joshua Homme was one. Vedder returned the favor the following day, joining QOTSA on lead cowbell for 'Little Sister.'

Unfortunately, I missed half of the aforementioned collaboration because, instead of going in early to catch all the bands, we opted to drink heavily in the parking lot until Queens hit the stage. Unbeknownst to us, they bumped all the set times up 15 minutes the second day. It was announced on their website, but we spent the weekend camping and partying, not buried in our smartphones (which had terrible service and were dead most of the weekend anyway). So you can imagine how pissed I was when, as we were walking in, I hear the beginning of 'Little Sister.' I was even more pissed when, halfway through the tune, we finally got the stage in view and realized Mr. Vedder had joined them.

Thanks to Lollapalooza in Chile, YouTube and concert promoters with extremely good taste, I was finally able to see what I had missed, as Eddie joined the Queens for yet another cowbell-fueled performance on April 6th. I hate to say it, but Ed even outdoes Will Ferrell, who previously performed the song with Homme and Co. on 'Saturday Night Live.' Check out both performances below and let us know who you think did better.

Pearl Jam have resumed work on their forthcoming tenth album -- which may or may not see the light of day this year -- while Queens of the Stone Age have finally finished their long-in-the-works album '...Like Clockwork,' which hits stores in June.

Eddie Vedder and QOTSA

Will Ferrell and QOTSA