When someone tries stealing your thunder when you are excitedly taking praise for something.
When someone tries to always outshine you.
Example 1:
I climbed mount everest without mount picks or a jacket. What am amazing feat for me!
Thunder Thief would say to everyone "Oh yeh, i did it without shoes, food or oxygen!"
Example 2:
You would say something like this to a group of your friends "I made the best cookies today."
Thunder Thief would say "Whatever they were total garbage. They were crusty and gross."
Reply: You are such a Thunder Thief.
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