My friend lost a bet. Punishment?

Hello all. One of my friends has lost a big bet to me that we were agreed upon the loser had to do something embarrassing (but not anything sexual). We are close friends but we also love to mess with each other.
Fortunately for me she lost, so I secretly asked her little sis for ideas to find out what she doesn't like (they kinda hate each other lol). And I've learned that very shy about her feet being seen by strangers.
So as punishment for the bet, I’m planning to make her spend a day in a mall but she must go barefoot throughout the day.
What do you think about this idea? Is it too cruel? Can you think of something else to make it better?
My friend lost a bet. Punishment?
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