MOST PEOPLE don't believe it, but fathers have fantasies about their children, too. Here are a few I've collected from fathers I've spoken to.

"Hello, Mr. Guilford. This is Nat Lefkowitz of the William Morris Theatrical Agency. I just saw your 12-year-old daughter perform in the school play at Holton Arms as the wicked stepmother in the production of 'Cinderella,' and I was so impressed with her performance that I was wondering if you could consider letting her play the lead in the road show of 'Annie,' the Broadway hit musical. It would pay $2,000 a week and we would, of course, see that you and her mother would be able to travel during the run."

"Mr. Minow, this is the chairman of the Coca-Cola Co. Your son's science teacher sent us a formula for a new diet soft drink that impressed us so much that we would like to buy it from him. Since he is till a minor we thought it best to talk to you. We are prepared to pay $100,000 for the formula and 1 cent royalty on every bottle sold. I'll give you my home number if you arrive at a decision."

"Hello, is this Mr. Harold Lachman? This is police sergeant Kelly at the 33d precinct. We have your son here. Before you get upset, let me explain that he dived into the river fully clothed and saved an 8-month-old baby from drowning. I was wondering if you would bring a dry set of clothes to the police station for him."

"Dad, I just wanted to tell you that you were right, and I was wrong. I'll never question your judgment again."

"Mr. Wanamaker. This is Dr. Winstead. Our laboratory made a terrible mistake on the pregnancy test and got the rabbits mixed up. Your daughter is suffering from nothing more than a bad stomach ache. I'm terribly sorry to have gotten you and your wife all upset - but you know how those things are."

"Dad, I'd like you to meet my new boyfriend, Arnold Rockefeller. He doesn't drink or smoke pot and works for his uncle David in the bank. Because of his hours, he has to bring me home no later than 11 o'clock at night. Arnold is interested in scouting. He has never had a traffic ticket for speeding. He loves to play golf and tennis. He would like you and mom to visit his family at Newport this summer. They could send their private plane for you any time you would like to do it."

"Hello, my name is Patrick O'Brien and I'm a scout for the Notre Dame football team. I just saw your son throw a football. I was wondering if he would be willing to go to Notre Dame on a four-year athletic scholarship. I can't promise you that he'll play first string in his freshman year, but from what I've seen so far, I would be amazed if the coach would want to keep him on the bench."

"Dad, I know this may not be the time to talk about it, but I just wanted to reassure you that when you retire I have every intention of supporting you in your old age. I'm only starting out in business, but I've set aside a part of my salary for a trust fund for your and Mom. As I rise up the ladder of success. I will put more and more in it. I hope you will be able to live on the interest from the fund, but I've set it up so you can touch the principal any time you and Mom want o take a trip or buy something. It's just my small way of saying 'think you for everything you've done.'"

"Mr. Melton, this is Time magazine calling. We're doing a cover story on your daughter, Jeannette, who has been named 'Person of The Year,' and we were wondering if one of our reporters could come out and interview you for it?"

"Mr. Sanford, this is the White House calling. The President would like to know if it would be all right for your daugher, Nancy, to sleep in the tree house with Amy overnight."