What do you mean by 'he s a yo-yo'?

Answer 1

That is a saying in Spanish instruction for people who constantly use the personal pronound "yo". It is not normally necessary, and marks the person as a novice.

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I don't really understand if the frase was primarily in English or spanish.

but assuming it was in spanish it can mean 2 things:

"yo" means "me/I" in spanish, so someone that is a "yo-yo" can mean it a narcissist person that can only think for him/herself.

but "yo-yo" it's also a toy (I think in English it's called the same)

so, someone that is a "yo-yo" can mean that it is a person that can be easily manipulated like a "yo-yo" or a person that changes humor or personality or ideas, very frequently. Also can be referd as a person, that comes and goes, easily (like in and out of relationships)