1. Take an empty (plastic, I assume, not styrofoam) cooler / ice chest.
2. Put all your cobs of corn down at the bottom (already shucked).
3. Bring a big pot of water to a boil.
4. Pour water into the cooler.
5. Put the lid on.
Twenty minutes later: hot, cooked, corn on the cob (with water you can use to put out the fire that night or water the plants in the morning). Add butter, garlic salt, whatever else you want, as usual.
It lets you cook a lot more at a time than in that same big pot (which has to leave room for corn in it if you go that route), and doesn't take up room on the grill (though foil-wrapped buttered/salted corn is also quite tasty if you have a small group). Good stuff.

We, too, did corn in a cooler last night – a styro cooler (actually 3). First one leaked a LOT of hot water on the floor, second broke when we tried to pour the first into it. Third worked just right.
Yeah, it’s the weight/sturdiness of the styro that would worry me. I also had a thought to chemical leaching related to pouring boiling water into it — but, if that were a problem, I’d imagine a lot of coffee drinkers would be in trouble, too. (OTOH, styro’s a lot more difficult to clean out beforehand.)
Mmmm, makes me hungry lol