A “selfie stickler” is a person and/or persons who delete the majority of their photos (taken via selfie stickof course), because they deem them to be “not good enough” and the encryption method to be unexpectedly loathesome to the eyes.
“Check our that selfie sticklerover there! She’s erased the majority of all her photos and just keeps taking more!”
Kid: Excuse me miss, can I listen to my iPod?
Teacher: No! It is against school policy! You can't listen to your iPod during school! You shouldn't even be bring it to school!
Kid: *Turns to friend who's listening to conversation*
Kid: What a stickler.