Has there ever been a time in the NFL when a team could score negative points?

Has there ever been a time in the NFL when a team could score negative points?

If so how is this done?

I was looking at a stat sheet of a team from the sixties and the_slot said -7 to 6.

How is this possible?

Please help

Tim, Wewahitchka, Florida
Please offer answers, ideas, & experiences for other visitors.
               From: Name  (Email optional)
Topic:
Comment:

Comments will be screened for suitability before being posted and therefore will not appear immediately.