The Berghain has its roots in the Ostgut club, that was exclusively gay in those days. The owners didn’t want to entirely loose their gay roots when they moved to the new location: that’s why, in the rear part of the Berghain through a separate entrance, you can find the Lab-Oratory (which already existed during the Ostgut days by the way, just as the Panoramabar).
The Lab-Oratory is not made for vulnerable souls. Every night has a different theme, almost always with a certain fetisj (sport clothes, leather, naked, etc). Only on friday nights there is no dresscode and everyone can wear (or not) what he wants to. In the magnificent, industrial setting men (women are not allowed) can do what they want with eachother. In the weekends you can often enter the Berghain at a reduced rate. Please mind: the doors only open two hours, to make sure that the number of visitors isn’t spread out too much throughout the night.