No Shrieking.

About 6 months ago Tiger started shrieking.  Always short bursts, and he always stopped before you said, "NO!"  He knows shrieking is not allowed because he will often say, "No shrieking!" after he has been warned about it repeatedly.  Tiger was warned about shrieking in church, and that isn't really a problem, he doesn't do it outdoors, he doesn't do it in public places (like the store) his shrieking is confined to inside the house, or inside the car and mostly for no reason at all.  

Since Blanket isn't really into crawling, he is mastering voice and hand gestures.  If you repeat his "dada" noises and then repeat them with a very simple gesture he will attempt the gesture/voice combination.  I wasn't very concerned about this until I realized that he was imitating Tiger's shrieks.   He is so good, that telling him "NO!" is egging him on.  He has no qualms about shrieking in church, or at the store, or at the park, or anywhere.   The funniest, or most frustrating part is when Tiger says,, "No shrieking!" to Blanket.  He doesn't even realize that his bad behavior is what brought about the great shriekfest in the first place.

I am seeking input on punishing both of them.  Mostly I am looking to punish Tiger, I am sure if he stops the shrieking Blanket will forget that he learned how for a couple of years.  

So if you see me and Blanket is shrieking in church, please punish Tiger for me!