That will fuck your knees up so fucking quick. Do not lock your knees out that the end of the movement. This stress will give you knee problems that not even a doctor can fix. If you use a Smith machine for squats make sure that your knees are not going over your toes. And also make sure you are not using too much weight.
Some assholes use too much weight.
They think they look cool, but they look like idiots. They are trying to get injured or something. Another thing is the angle of your legs. Next time you squat or use the leg press keep an eye on the angle of your legs as they pertain to your feet. Make sure your knees go over your feet.