The term "Skywalking" is a code/ innuendo for having sexual intercourse.
Steve: Details bro, details!
James: We hit the movies and afterwards when I was taking her home she started taking it like a champ. It felt great.
Steve: Damn, did you guys start Skywalking?
James: Na dude. We got spooked by a car passing by.
Steve: Damn. Better luck next time bro.