I like the figurative meaning of this phrase, as it makes me think the person has shrunk and now fits in your pocket.

We use it when we do something that makes other people like you or do what you ask from them:

• Con ese gol, “el cóndor” Rueda se puso a los hinchas en el bolsillo.
• Cuando dijo que somos el mejor público del mundo, se puso a los argentinos en el bolsillo.
• Se puso a mis viejos en el bolsillo

You might also want to read these articles:

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• All Argentinian Food
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• Cachengue
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• Something is better than nothing
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• Estar chocho/a
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