How do I convince my dad to let me meet this guy?

I met a man online who has a Himalayan male. I have a Siamese female. We want to mate our cats. But how do I convince my dad to let me give away the cat for a few days?
(And should I even trust this man?)

You have no way of knowing whether this guy is interested in your cat or interested in you. This is the typical kind of scenario that pedophiles use to meet young people. You should not meet him unless your dad goes with you.