Here's what I would say:
"Allison, you're cute and clearly you were born with an amazing set of pipes.
But you're 16.
No 16-year-old should sing that song. Ever.
Ever. Ever. Ever.
I know it's unrealistic to expect American Idol to have the highest moral standards, but I think even they could adhere to this basic rule of thumb: you shouldn't be singing about sex if you're still wearing braces.
I really don't think that's too much to ask.