have a mind of (one's)/its own

To have the propensity or ability to think, act, or form opinions without outside influence. It is often used (humorously) to describe an inanimate object that cannot be controlled by its owner. I tried to tell him that wasn't the best decision to make under those circumstances, but you know he has a mind of his own, and he did it anyway. I swear, my vacuum has a mind of its own! It turns on in the middle of the night when we're all asleep! Good luck feeding that paper back into the printer—that thing has a mind of its own!

have a mind of your own

1 be capable of independent opinion or action. 2 (of an inanimate object) seem capable of thought and desire, especially by behaving contrary to the will of the person using it.

have a mind of your ˈown

1 (of people) have your own opinion and make your own decisions without being influenced by other people: She certainly doesn’t need your advice; she’s got a mind of her own, that girl.
2 (humorous) (of machines, etc.) behave in a way that you do not expect: This photocopier has a mind of its own. If I ask for ten copies it does one; if I ask for five, it does fifteen.