Gravity Check

The term originates from hackey-sack. A gravity check is when an easily playable sack hits the ground only because it was coming down equidistant between two or more players and each player didn't make an attempt because they thought someone else would play it.

The term can also be used in business to describe a situation where nobody on the team works on a task because they think someone else must already be working on it.

Your boss emails the whole team, "Gravity check. Earlier I sent an email to all of you asking that one of you please call the client today. Did any of you actually call the client?"