How do I write a memo explaining the exceptions of staff with regard to teamwork in keeping th office and bathroom clean during the day and in between janitorial visits?

My favorite has always been;

This workplace is your home 5 days of the week. Please keep it clean, like you would your own home. Your mommy doesn't work here, and she won't clean up after you. As an adult, you are expected to clean up after yourself. Thank you.