Toilet paper isn't the first thing that comes to mind when you want a hot meal, but when you're camping or out in the field (i.e. military training), a little TP is the difference between cold tuna and luxury.
As redditor drdesparche points out, Israeli military forces are fed a lot of canned tuna. To make it just a little bit better than plain, cold tuna, they cook it right in its own can using a piece of oil-soaked toilet paper on fire.
This food hack will only work with tuna fish in oil, not in water. Obviously, it's ideal to use unscented and unmedicated toilet paper, and skip the recycled kinds that are known to include bisphenol A (BPA).
Again, make sure you have tuna with oil, otherwise this will not work. Do not dump any of the oil out of the cans, as you need it for the cooking. For each can, you need three sheets of toilet paper.
Add three sheets of two-ply to each can and soak until completely covered in oil. Try not to spill any oil, and make sure there are some gaps (holes) in-between the oil-soaked paper and the can, because you don't want to create a seal.
In a well-ventilated area (e.g. outside), light each corner of the TP and wait for the fire to spread. Drdesparche states that this TP could burn for up to 25 minutes, which is when it'll be done.
For a more subtle flavor, you can blow it out and remove it whenever you want. The heavy oil should prevent any floating embers from getting away from you and starting a fire nearby, but it's still a good idea to be extra careful.
Once it's all done, just remove the charred layer of TP and flick off any remaining ashes.
Then enjoy your warm can of TP-smoked tuna.
If the U.S. military were given tuna cans instead of MREs as rations, I'd imagine this would be a fairly popular food hack amongst troops, but they already have a few tuna MREs to choose from.