Only if you are ready to accept the consequences. Poking is a statement of pure, unscripted intent. You are saying, "I acknowledge your existence, but I have nothing concrete to say about it." It’s the social equivalent of a cough. A very intentional, targeted cough.
If you poke a crush, be ready for a "What does that mean?" text. If you poke your mom, she will call you to ask if Facebook is broken. But if you poke your best friend, they will likely poke you back, and you will both have a private, silent laugh. That, my friends, is the magic of the poke.
So go ahead. Open Facebook. Find that one guy from college who always posts about his sourdough starter. Give him a poke. It’s meaningless, it’s weird, and it’s wonderfully human. Just don’t ask me to explain it to your grandmother.