One can earn this badge by getting a39C3 friends badge gifted from a friend who made it at the 39C3 LED badge soldering workshop and visiting the TBD assembly. The 39C3 LED badge reacts to the presence of friends in its vicinity, which includes the TBD friends badges.

There is also a completely different badge (39C3 friends badge badge) that you can earn by participating in the 39C3 friends badge soldering workshop and visiting the TBD assembly.

TBD friends badges also count as a 39C3 friends' friends badge