Yeah Unknown Zone, I did have something along this issue some time back. I guess I would play the would be wide in this case because I know I was doinbg the dirty texts and I was trying to keep them away from my wife.
I ended up using an app called
EasyHelper SMS Security which really worked well and did exactly what I wanted it to do. The only real issue I had is that you have to use the OEM txt client and cannot use something like the threaded txt client many of us likely use.
The thread link below will give some more info and description
http://forum.ppcgeeks.com/showthread.php?t=12543