Separate names with a comma.
How very curious.
Sorry about that, I went to bed. Sharing titles? That would probably be the option to disable showing what you're playing in your friends list.
Open your Friends List, click Settings, then the first option and you should be able to disable showing your friends what you're playing. Since homebrew stuff can show up in there, it's bad for you to have.
You should also go to your Settings menu and find the SpotPass options, turn both of them off (obviously sending data to Nintendo, but also receiving them... you won't need SpotPass even for games with DLC, anyway, thanks to CIA installs).