I would strongly advise against putting a Krystal burger or any other fast-food burger in a toaster. Toasters are designed to toast bread, not cook or heat up items like burgers.
Putting a burger in a toaster can lead to several potential issues:
Fire hazard: Burgers have a higher fat content than bread, and the grease can cause the toaster to catch fire, creating a dangerous situation.
Mess and damage: The burger could fall apart inside the toaster, making a mess and potentially damaging the appliance.
Uneven cooking: Toaster elements are not meant for cooking burgers, so the result would likely be unevenly cooked and unappetizing.
If you want to reheat a Krystal burger, it's better to use a conventional oven, microwave, or stovetop. However, keep in mind that reheating fast-food burgers may result in a loss of quality, as they are designed to be consumed immediately after cooking. It's always best to enjoy them fresh if possible.