So you're wondering about the Facebook poke, it's a pretty old feature but still gets used today. From what I've seen, people usually poke someone on Facebook as a way to get their attention or just to say hello, it's like a casual wave. Sometimes it can be flirtatious, but it really depends on the context and who's doing the poking. If someone pokes you, you can either poke them back, send a message, or just ignore it, it's up to you. I've had friends poke me just to start a conversation or to see if I'm online, so it's not usually a big deal.