Crime and punishment

I have once again been outsmarted by my toddler. At work today Eli kept throwing his toys. Because he can very easily start setting a bad example for the other kids, I am a little stricter there than I am at home. He gets no warnings, but is sent straight to time-out. It did not take very long before Eli figured out that he could do what he wanted as long as he was willing to deal with the consequences. Soon he was throwing toys, and then immediately putting himself in time-out. Once he just pretended to throw a toy and gave himself a punishment.

What is worse is that he is pretty cute in time-out. He just sits and faces the wall. He (usually) doesn't cry, or get upset, or beg to get up. Just sits there. Occasionally he will let out a really loud sigh, to let us know that he is bored. If he is really bored, he will make popping sounds with his mouth. Like Donkey in Shrek 2 when they are traveling to Far Far Away. I have to leave the room to keep from laughing, because laughing will just encourage him. How can I punish him when really I just find him amusing.

I really wish that I could find the instruction manual that came with him.