What makes the white MacBook overheat?

I heard that Macs sometimes will overheat, new macs. I am going to get a MacBook white in January and I want to know what does it take to overheat a white MacBook? YES I do know about SmcFanControl and how it works, I want to know what does it take to make a MacBook overheat without the program running.

just lay it on the bed for a little while
Where did you hear that? There’s no truth to that when made as global statement about MacBooks, but there are certainly things you can do to overheat ANY laptop. Such as, running a task that maxes the processor at 100% for an extended period while in an overly hot environment or on a blanket or soft surface that blocks the ventilation.

Your Mac will cool itself automatically; SMC Fan control is unnecessary. Many people think that when their computer feels hot that it’s overheating. That’s not necessarily true. When a computer overheats it crashes, but heat without a crash is totally normal. If it makes your lap uncomfortable, you can try one of those laptop cooling pads.
The plastic of the white one doesn’t conduct heat very well, so don’t try to use it in bed when it’s sittin on a blanket or your girlfriend’s behind.. It needs ventilation. The fan will speed up. It doesn’t take much for it to get too hot.