One morning, three persons decided to fish. An old man, an old guy, and an old boy. They decided to fish not in the same ponds, so they look in different places. When the afternoon came, old guy and old man have seen each other. I heard their conversation and they said the following:
Old guy: So how many fish did you get?
Old man: I think this isn't the lucky day for me. That's why I got nothing. Not even a nibble.
Old guy: Really? May I see your basket?
Old man: I don't need to show it to you just to prove you that I'm not lying.
Old guy: O.K.! I won't insist.
Old man: So how about you?
Old guy: I got three fishes. One for me. One for my wife. And one for my kid.
Old man: I thought you are single?
Old guy: That's just what you thought. Lol.
Then the old boy came.
Old boy: Woohoo! I got twelve. I'm so happy!
Old man: Really? Then that's good!
Old boy: I'll give one-sixth for my friend. One-fourth for my grandparents. One-half for my parents.
Old guy: Wow! I never thought your grandparents are still alive.
Old boy: They are indeed.
Out of the given information above, who do you think is lying in the story (who's not telling the truth?)? If you say so, prove that the person you have chosen is the one not telling the truth.