<ul data-eligibleForWebStory="true">Hacks include prank traffic lights, classroom Rickroll, robot vacuums, Lenovo website, Twitter pranks.Hackers targeted traffic lights with Zuckerberg and Musk voices, students performed classroom Rickroll.Ecovacs robot vacuums hacked, Lenovo website defaced, Twitter accounts hijacked for pranks.Lessons learned: avoid weak passwords, use strong, unique passwords for online security.