A Daily Mail story that pet parrot Wunsy scared off an attacker who grabbed her 25 year old owner Rachel Mancino in Sunny Hill Park, Hendon, London, by squawking and flapping its wings, drew the headline 'Peck On Someone Your Own Size', substituting 'Peck' for 'Pick'.

To peck is used to describe a bird striking or biting something with its beak.  The phrase 'pick on someone your own size' is usually said to someone who wants to fight a person who is smaller than they are.