First of all, Global Citizen is a charity that aims to end extreme poverty, so this was a very good cause for all of these celebs to come out and support (although I don't know how much money the event raised, if any -- and that's not shade, I just don't know if that was the purpose of this particular concert, which was, regardless, hugely supported by politicians and musicians alike. The program is going to air on TV later this year, and that may provide a fund-raising aspect?). Personally, I am always fascinated by how the celebrity guests at these sorts of things choose to dress themselves, because I think it must be VERY hard to parse for them and their stylists. It's for charity, so don't show up wearing something too attention-grabbing. But there's a red carpet, so you can't just shuffle up in your grubbies, or you'll look like you don't care. But it's also outside in a park, so you don't want to look too fancy or you might look crazy. But also Michelle Obama is going to make an appearance. I feel like anyone would have a fair amount of back-and-forth, and, indeed, you will see that in the red carpet...if you care to join me. [Photos: Getty]