Facebook Sneak

a user on Facebook who repeatedly activates or de-activates their personal profile and/or blocks and unblocks the profiles of various people in order to accomplish one or both of the following:

a. sneak in and out of another person's account to see what they are up to and with whom without them knowing they've been there;
b. prevent certain people from knowing where and with whom they were sneaking around with.

I wish Paul would stop being a Facebook Sneak! He blocks and unblocks me before I can unfriend him in my profile settings!