Bob is correct on the highest recorded temperature, at least from the last time I checked. People do tend to exaggerate temperatures.
Well, it's a bit unfair to quote statistics that for the most part only come from places where people have the money to put into these surveys. Many parts of the world are probably just as hot as Death Valley, but no one has ever recorded the temperatures. It is impossible for those who do these recordings to be everywhere, especially in very remote, very poor countries that no one has an interest in going to. And how many temperatures, even in Death Valley, have turned up, but gone unrecorded because no one was there to record them?
Take a look at Dallol, Ethiopia, which has the record for the average highest temperature on Earth. Who knows what the highest temperature in this region, which is extremely remote and virtually unknown to most westerners until recently, might at one time have been?
Humidity makes a huge difference in how well one can stand the heat. At least with dry heat you can find shade and get relief that way. Even with lower temperatures, humid heat is unrelenting. You can't get away from it unless you have an enclosed, air conditioned place. The air doesn't cool at night. And because of the humidity your perspiration doesn't cool you. So drinking doesn't much help either. A fan only barely. Top that with a far greater number of insects that love the humidity, and you've got really miserable conditions. Getting in a sleeping bag can be awful, even a thin one. Even just a mesh canopy, which stills the air, can exacerbate the misery of the heat. Your clothes are constantly wet from perspiration, but synthetics don't breathe well, so that makes them feel hotter, and they stick to you. Cotton, silk, linen, hemp, pineapple, and bamboo cloth are the only materials that work in these conditions. Wool just feels very hot and holds all your moisture. The danger here is not hypothermia, but hyperthermia, over-heating. You can get very sick and die from heat exhaustion or heat stroke. If the temperature gets high enough, there is a point where just walking takes too much energy. That's why most Southeast Asians get up at dawn, when it is slightly cooler, take a break during mid-day, and are again active in the evening. They think a lot of sun-burned, red-skinned, rolling-with-sweat western tourists have lost their minds.