The lost and found area usually located on the stage after a concert involving a mosh pit. Since people tend to lose shoes, cell phones, hats, sunglasses, etc in the mosh pit, after people start to clear out after the band is done playing these items are picked up and brought to the stage crew who put them on the stage. Often times if there's an MC, they'll announce an overview of the items like "If you're missing a pink cell phone or a size 12 left shoe, it's on the stage."
Oh crap, my cell phone isn't in my pocket! I'll go see if it's in the moshed and found.