I used to make fun of my aunt with down syndrome
Why would you ever make fun of your aunt for having down syndrome?
I know it is really mean, but i really enjoy teasing her.
Even though it can be fun to tease our loved ones, making fun of someone with Down Syndrome is completely unacceptable.  Your aunt has to face this kind of ridicule on a daily basis from people who truly mean harm, so her life is hard enough without you joining in.  I'm glad that you have learned not to tease her any longer, and I hope that you can teach your kids to be respectful of all others.
But I'm always with her and she loves it! Liar!
You just should really try harder to be nice to your aunt. Someone living with down syndrome has plenty to worried about besides having to deal with you make fun of her.