What happened to a friend of mine, he decided to pay for a bj, round the back of some shops in Patong, and with his trousers round his ankles, he had already paid said person and then pulled up his trousers and headed off. Then he realised his wallet was stolen while his trousers were on the floor round his ankles.
I have a habit I have got into, a sort of routine where no matter where I am I always check, wallet, keys & mobile. If they are not where they should be on my person, I then start to worry and panic.
But front pocket is a must for anything important, because its extremely hard to steal from the front pocket. The back pocket just isn't a good pocket. In fact I would go as far to say its a bad pocket and should be removed or sewn up altogether.
E