"Getting it right" for this particular trick question means saying "Hey, roosters can't lay eggs". If someone tries to figure out which way the egg will roll then they've missed the trick. In most cases the person's response will tell you whether they caught the trick or not, though in the case of someone who just looks at you like you're dumb and doesn't say anything I will grant that you wouldn't be able to tell until they said something. But their first verbal response would probably reveal whether they saw through the trick question or not.