Your dad is mistaken. They're illegal to own as pets and very dangerous. Very expensive and time-consuming, too.
I RARELY ever see people suggesting pet monkeys. They can be dirty, are very high-maintanence, and are a LOT of money. Not to mention you also need a lot of room.
stop smoking dope
Does you dad have 50 to 100 thousand dollars to buy you a monkey through the black market. If you are in the US it has been illegal to buy and sell primates since 2009, when the woman in Connecticut was viciously attacked by the chimp. Only zoos and wildlife refuges are allowed to own them with special permits and licenses.