You can't. The only tip i can give you is if you are cooking a tv dinner, don't remove the plastic wrapping but instead add all the time up and cook it for the time you have added. After you do that, heat and you will be done. The things is, if you take food out of the oven or microwave, it starts to lose heat if still frozen or not cooked all the way; so it is best to cook it all the way through and not lose any heat.
Thermal camera or scanner. The size of the chunk of meat, the oven temp, and time in there can all be charted to make an accurate estimate. Understand? Prob both of these suggestions are more technical than you wanted but that is how a scientist would approach the question. .
For that to happen you would have to have a lot os experience with temperature variances using your finger. This means using your finger to test EVERYTHING for temperature differences. In this manner, you will be able to learn how the various temperature differences feel. I think it should be obvious that this is a very dangerous practice. This is why no one does it. Don't be cheap and simply get a thermometer. Don't be dumb and decide to get a mercury thermometer. Most mercury thermometers will max out at around 150 F. Foods at 250 F will cause it to burst (water boils at 212 F). Mercury mixed with pieces of glass in your hamburger is always bad.