Often followed by, "I'm too old," which I'm sure I will laugh at in ten years time. And it won't be true until I'm twice this age, with any luck.
Technically, sure, I can do that semi-gymnastic manoeuvre you're pulling, kid. I just don't want to. And I don't want to argue.
So I lie, and say that it's just not possible. Mummy is basically decrepit. She would break if she tried it.