Stop when you are ahead, Joke

My wife bought a new line of expensive cosmetics guaranteed to make her look years younger. After a lengthy sitting before the mirror applying the 'miracle' products, she asked, 'Darling, honestly, what age would you say I am?'
Looking over her carefully, I replied, 'Judging from your skin, twenty; your hair, eighteen; and your figure, twenty five.'
'Oh, you flatterer!' she gushed.
'Hey, wait a minute!' I interrupted. 'I haven't added them up yet.' 

And that's when the fight started...