By nature, memes are very public things. They are made to be spread far and wide, as well as manipulated and changed by anyone who comes across them and wishes to do so. They go hand in hand with the concept of being viral, so there isn't much room for privacy. It is what it is.
At the same time, we often pick and choose the kind of memes we share depending on our audience. We probably aren't going to send the same things to our mom that we would our best friend. There are even the ones that we might relate to and find funny, but not want to share our opinion of that far and wide. In this way, memes also have a kind of secret side to them. It's up to you on which side of the fence fall all the examples below. Maybe they are a mixture.