Don't know what Slack is? Then you probably don't work in an office. The communication tool is like e-mail, but better -- and it's taking over workplaces across America. In this week's episode, Francesca and Rebecca break down the enterprise software phenomenon: How it works, who uses it, and why people are so obsessed with it. Dayna Evans, a writer for New York magazine, who has written about her complicated relationship with Slack, joins them to also discuss some potential downsides of chatting with coworkers all day.