A poke is a jab or a sharp push, usually with something thin or pointed, like a finger, a stick, or even an elbow.
The main idea behind a poke is a prodding action that creates a depression or hole, as when you poke someone in the ribs with your finger. It can also mean a quick, sharp movement, like when a turtle pokes its head out of its shell. Still, the word often has a less-than-pleasant feeling to it, like something not really dangerous but still annoying. We often say a tolerable experience is "better than a poke in the eye with a sharp stick." It can also take on a more figurative meaning — when you "poke your nose into someone else's business," it means that you are intruding in another's private matters.