Chop your tomatoes into a small dice and discard the guts, leaving just the flesh. Place into a large bowl.
Chop your red onion into the same size and add to the tomatoes.
Cut your jalapenos into a small dice and add to the tomatoes. If you want a milder heat, remove the seeds and white ribs as this is where most of the heat is. If you leave them in, each bite will have more heat from those parts.
Add the corn kernels to the mixture.
Chop the cilantro by hand and add to the bowl. Mix.
Juice the limes into the tomato mixture and add the salt. Mix again.
Refrigerate the pico for at least two hours or until chilled. This can be done overnight. The longer it sits, the salt will pull moisture out of the tomatoes and make a sauce. You can choose to make this in advance and add the salt just before serving to minimize the moisture that comes out.