Take a look at our video above for your sneak peek of Dunham trying to get though a scene of sexy role-playing without busting up laughing. Of course it doesn't help that her co-star Adam Driver is struggling to keep it together as well.
"I'm so sorry you guys," Dunham says to her crew through a fit of uncontrollable giggles. "I'm going to just take one second. Don’t cut, please!"
For more hilarious unseen moments, fans can pick up Girls: The Complete Third Season on DVD or Blu-ray on Tuesday, Jan. 6.