Tiredness => Can't Dance well?!

We were travelling back home in th car in the late night, and my wife was so tired after the shopping.

Then she talked to the kids and it went on like this:

Mummy: "It's already past my bedtime and I really need your help to pack your bags so that I could sleep as soon as possible. Otherwise, I will not be able to PERFORM well in my work tomorrow."

Kid: "Mummy, I thought you work as an accountant, so why do you need to DANCE well in your work tomorrow?"