Learn Italian: Io non c'entro niente con questo scherzo! - I have nothing to do with this prank!

C'entro comes from the pronominal verb entrarci. While it literally means "to fit inside" or "to enter there", it is very commonly used idiomatically to mean "to have to do with" or "to be relevant". So, non c'entro niente translates to "I have nothing to do with it."

Why do we use the double negative non ... niente here?

In Italian, if a negative word like niente (nothing) comes after the verb, you must put non before the verb. So, non c'entro niente is grammatically required here. If you left out the non, it would be incorrect.

How would I change this to say "He has nothing to do with this prank"?

You just conjugate the core verb entrare for the third-person singular and keep the pronoun ci (which drops its "i" before the vowel). "He has nothing to do with it" becomes lui non c'entra niente.

Why is the subject pronoun io included when Italian usually drops it?

In this context, using io adds strong emphasis. The speaker is being defensive, essentially pointing the finger away from themselves to say, "I have nothing to do with this prank!"

Could I use the phrase instead of here?