There are three possible colors of hats worn by three people: two black and one white; One black and two white; Three glasses of white wine. If two are black and one is white, then a person can definitely see the other two are wearing black hats, thus immediately judging that he is wearing a white hat and won't "hesitate", so it won't be two black and one white. So it can only be one black, two white or three white. That is, at least one of the three people is wearing a black hat. At the moment of "hesitation", all three clever students realized it. At this time, every student is thinking, "If I wear a black hat, then the other two people should guess that they are wearing a white hat." Everyone hesitated whether to eat or not and saw them wearing white hats.

So, three students guessed that they were wearing a white hat almost at the same time.