Sorry D.O., Disagree STRONGLY. Just the other day, I picked up my coke and when the lid is not on correctly, the cup deforms inward, the lid pops off, and the contents spill all over your lap - and I hadn't even come CLOSE to getting it in my mouth yet! When the lid is on correctly, it provides the support to maintain the "O" on the top of the cup - which keeps all of the above from occurring.
Try it sometime.
Don't be sorry, I think you make a good point that I had overlooked. Thanks.
But that's a soda cup. Soda cups are larger and made of paper not styrofoam (also depends on how you hold it, the further down you grab it the less deformation of the O). Coffee cups are at most 20 ounces and good thick styrofoam, when I worked in McHell we didn't even give lids to the "for here" orders that were drinking coffee, everybody would just take them off and leave them that way (obviously if the customer asked for one they got it). The coffee really only needs a lid if it's going to be jostled.
Now it is possible she spilled a little and spasmed in such a way that she over squeezed the cup and ruptured it that way. But Stevieboy pointed out the big one: those McD's hot drink lids can't be drunk from without user interaction (tearing off the drinking hole). She monkeyed with it last, if the lid was lose that's her fault. Though personally given the careful consideration as to why there are no scars (I'm betting there are no pictures nor medical documentation either) I think the whole thing is a fake. Normally people can't tell you why a large burn didn't leave any scars, but she's got it right in the story.