He was hinting at you what to do, but as a normal, well-adjusted person, you weren't going to get that hint.
He should have just told you - you needed to scare the shit out of them with threats.
Here's how the meeting would have gone.
First you let them relax and think you're going to give in... say some nice things with a little smile on your face... "We are always interested in your ideas."
Then your mood changes and becomes serious.
"However, you refused a direct order from management. It wasn't a mistake or an oversight - you deliberately went behind everyone's back.
"This was dishonest. [pause - do not let them speak - hold your hand up or talk over them if they do]
"I shouldn't have to remind you that dishonesty and deliberately disobeying management are both grounds for dismissal from this company. A repetition of this offense will have the gravest consequences.
"I have placed a letter in your permanent record to this effect. For the time being, you will send all materials directly through me before anyone else sees them."
Now lighten up a bit. "This job is very important to me. I want us to do really well, and the best way is if you work with me and not against me. If you are willing to cooperate, we can go far - but future pranks like this will damage your future with this company."
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Have I ever done this? Hell, no, I am a creative guy, not a manager.
Was there anyway you were going to turn into that aggressive person that would have saved your job? Probably not.
You probably needed a mentor to explain to you how to be firm and aggressive without being angry or taking it personally. You shouldn't have to do this, but Anglo-Saxon males are naturally aggressive and so react with submission to a bigger display of confident aggression, like all primates do.
My insight in these matters came through decades of experience. Even a half-an-hour of explanation from me-now to me-in-my-twenties would have saved me a lot of grief.