Take a kitchen knife, open the cooktop, and try to cut the chicken thighs. If the chicken is sliced easily, then it has been cooked. Color is another way of telling whether the chicken is prepared or not. Properly boiling lightens the pinkish color of the chicken. If the chicken loosens its original pink color, then it has been ready to eat. Whether the chicken thighs are cooked or not, you also can tell it by their temperature. Insert a thermometer inside the chicken and check its temperature. If the temperature rises up to 160 degrees, then the chicken thighs are cooked.