You can squash a guy's eyeballs in or knee him in the groin. Its not for the faint of heart but its your life or the bad guy's, its no time to be squeamish.
Actually, both are much harder than they look. Most people will turn away in time to prevent a proper eyeball squash - miss by an inch and you'll hit bone instead- and the knee to the groin usually hits thigh muscle. You would be surprised at how few guys will stand there with their legs spread apart waiting for a groin shot.