If she asks you if you notice anything different, do not say "no", take your best guess, hair cut, new outfit, anything, if you are right, you win, if you are not, compliment her on whatever you did guess and ask her what is different.
If she asks you if you notice anything different, do not say "no", take your best guess, hair cut, new outfit, anything, if you are right, you win, if you are not, compliment her on whatever you did guess and ask her what is different.