Shameless plug since it's relevant: We built a Slack bot [0] that shames (in good humor) people in the office who leave unlocked laptops unattended. We had a similar system at Twitter where we would tweet a certain codeword on unlocked laptops and it was very effective in stopping that behavior. [0] https://sniped.app/
It's recently escalated to sudolphin-ing (think a sudo alias involving cowsay and you're on the right track).