I earned this badge by using my iPhone app to check-in for 6 days in a row. It was tricky because I almost missed day 4. In total, I checked in 14 times (in 6 days) because I was trying to earn the Domestic Badge.
I’m finding that’s what happens: I’m going for one badge, but I earn another. I got 4 this week. Soon it will get harder and harder as the easier ones will have been completed.