Facebook Reciprocity
You feel like you have to like or comment on someone's post just because they've been kind to you, even if their post is about their pet's hairball and you're too lazy to block them.
I liked your post about your dog's hairball because you've been commenting on my memes, and I'm too lazy to block you.
I commented on your rant about your dad just to be nice, even though it was annoying.
I liked your stupid post about your uncle's pizza because you were nice to me, and I'm too tired to block you.