need a good punishment!

We’ve been using his CB for a few months. These days I usually only lock him up every now and then for a day or so. It really turns me on knowing he can’t touch himself until I give the word. He’s incredibly affectionate after wearing it all day, which I love! On the last couple of occasions when he acted “bad”, I just left him in the device and skipped visiting his house that night as punishment. However, I discovered that he managed to pick the lock during one of those overnight stays. I went over to surprise him only to find it off with him having jerked off! What do you think I should do? I considered using small plastic locks, but they seem so easy to cut open. How can I make sure there’s absolutely NO WAY he removes it?