Warning: Do not attempt to use these techniques against your human colleagues or family members. They may not appreciate it.
Use a fedora and a trench coat to blend in with the robot crowd. It's like they say: 'Dress for the job you want, not the robot you're trying to hack.'
Build a fake social network of robots, and slowly introduce your target robot into the group, gaining its trust, and eventually, its secrets.
Use your knowledge of robot psychology to create a fake phishing site that looks like a real robot interface. Then, wait for the robot to walk right into your trap.