Shrinking you down and taking you shopping with me

You're far too tall, do you know that? I want to go shopping and I will need your help (you don't really expect me to carry things do you?), but I can't have you scene stealing like this. Luckily I'm a witch, and I know a magic spell that will make you a little shorter... Humans are that height aren't you? Oh whoops, turns out I forgot how to end the spell and you're going to keep shrinking smaller.... And smaller... And smaller still!