Mol an óige agus tiocfaidh sí, Guest - "praise youth and it'll come on". Ignore bad behaviour and pay attention (preferably without comment, but with interest and food) to good behaviour.

Teenagers (and for young men this often goes on well into their mid-20s) are put on this earth as a trial of strength for their parents. Hold strong and be on your kid's site (though not on the side of any wrongdoing) and you'll pull through together.