poke one's nose into

To involve or insert oneself in an intrusive or nosy manner into something that is not one's business or responsibility. I wish our neighbors would quit poking their noses in and just leave us alone! Don't poke your nose into your brother's affairs—he can manage well enough on his own.

Pry into or meddle in another's affairs, as in I told her to stop poking her nose into our business. This usage replaced the earlier thrust one's nose into in the mid-1800s.

To interfere, to meddle. This term began as thrust one’s nose into someone’s affairs, back in the sixteenth century. The analogy presumably is to a dog or other animal nosing about. Samuel Johnson used it in his Dictionary under “Nose” (1755): “To thrust one’s Nose into the affairs of others, to be meddling with other people’s matters.” In America at some point poke was substituted.