EXCLUSIVE

Black Keys guitarist Dan Auerbach and Jen Goodall said "I do" ... and they made all their reception employees swear "I won't" bad-mouth the bride, the groom or anything about their big day.

Dan and Jen tied the knot Saturday at his home in Nashville, and made everyone working the ceremony sign a confidentiality agreement ... which is not uncommon for a celeb wedding.

However, this contract wasn't about protecting details like the gown designer or the menu -- it was all about blocking trash talk. We're told anyone who does say a nasty word about Dan or Jen will be dragged to court.