Lol, you ALL (well, most) were thinking that was a poison ivy reaction and I knew right off it was a burn. Even GhostFL confirmed it.
But, dude, that is one serious burn, you really want to go get that checked by a professional. Me, personally, I usually drain the fluids off right away so it doesn't turn into that, but that is because I only get minor burns usually.
If you can manage, don't pop it unless you are advised to do so by a doctor, or better yet, have one do it for you to make sure it doesn't get infected.
You should have put in the first post that you burned it... lol...