steal someone’s thunder

(verb) to take credit for something that someone else did

Example Sentences:

My partner stole my thunder when he told the professor that he did all the work on the presentation.

The businessman alwayssteals his partner’s thunder by using his ideas.

A: I think we should do our presentation about Stem Cell Research.
B: Great idea! I’m going to tell the professor!
A: I should tell the professor because it was my idea. Stop stealing my thunder!

From the Blogs:

Why Facebook isn’t poised to Steal Twitter’s Thunder

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