What is a good punishment for flirting with someone other than your dominant wife

Yesterday evening, my wife and I were at the store. We went to different parts of the store. Then a young woman started flirting with me. I flirted back a little bit just as my wife walked up behind me. In the car on the way home, she told me that I am going to be severely punished for that and that I have to pick the punishment. She said that the punishment must be physically painful and humiliating and something that her friends can help her administer. Plus it has to been done outside in a public place.

You can PM me if you don't want to post here

Does anyone have any suggestions at all?

I suck at coming up with good punishments. That's why she is making me come up with the punishment. I can't think of anything good that can be done outside in a public place.
Every 12 hours that I don't have a good punishment, I get 3 cracks of the whip on my balls each leaving a welt and every 24 hours after the first set, that number doubles. I've already got the first 3 welts and at 6pm Eastern time today, I get 3 more welts if I don't have a good punishment. Then at 6am tomorrow morning, I'll get 6 welts and do forth.
If I don't have a punishment by 8am Saturday, she'll pick it and she promises that if she has to pick it, the punishment will be severe.

I really need some suggestions.

So, if you have any good suggestions, please reply with your answer either here or in a private message.
All suggestions are greatly appreciated.

Thanks