How can I convince my dad to allow me to have a pet?

My dad keeps saying: we don't have the money, I say I use my own. Now, he says: We don't have time for it, I said I'll do everything for it. Now, he says ''theres a bunch of starving people out there, stop this non sense. Then, I say, everytime I want to donate, he says no. Then, he also says it will smell. But, I said I will pick up poop daily, which is what your supposed to do with a tortoise. I already researched about this animal enough, and took FULL responsibilities. What should I do?