How do you convince your parents to buy you a Rainbow Unicorn Pillow Pet right now today

Tell them that you love unicorns and that you really want to have one. If they say no. Tell them that you have money to pay them back (if you buy it online). If they still say no then just keep quiet about it then tell your mum that you are just going to wash up or hoover and she might say ok because you are helping clean up. I have a pillow pet but its really rough now and isnt soft or fluffy. i really want one but im not allowed another but i am trying my best