Rabbit is the error code you see when someone in your fireteam had a connection problem and the game tried but failed to keep the fireteam together by returning to orbit. If you're playing with friends, make sure they've all gone through the [url=https://www.bungie.net/en/Support/Troubleshoot?oid=12915]Network Troubleshooting Guide[/url] and checked our help page for any other error codes they're seeing.