Wundaweb®

Wundaweb® (much like 'Hoover') has become the generic term for hemming web. Anyway, for the uninitiated, this stuff is magic. For repairs and hemming, it was invented for the non-sewing amongst us. Trouser hem come down? Fret not. 

Cut a strip the length you need, put it between the folded up hem, cover with a damp cloth and press. Done.

Still too much for you? We have safety pins too (or you could just stay in).