I thought I saw on Oink's signup a toggle that let you opt-in to auto-following other users. I was surprised to see that as usually it's opt-out (if at all). What this seems like to me is a glitch on Oink's end - not following their own preference options they expose to their users.
edit: I definitely didn't mark down to auto follow my friends. I just got the pig sound notification and it scared me half to death. Oooh boy my heart is racing.
There's an option to disable auto-syncing as they call it, and it's on by default. Interestingly enough, when I went to check out the settings area just now, I saw several Twitter friends who I wasn't friends with yet, despite having auto-syncing turned on, so this looks like a bug on their end. I got an error when I tried to check my Facebook friends' status as well.
There's also an option to toggle being notified when a friend joins (presumably this refers to auto-syncing), which is on by default too.
edit: I definitely didn't mark down to auto follow my friends. I just got the pig sound notification and it scared me half to death. Oooh boy my heart is racing.