Unless you’re in a service or construction industry, we wouldn’t expect you to know what a “cold weld” is. It happens when the temperature of the two mating metals does not reach the proper level to assure adhesion over time. They’re almost impossible to identify, and they don’t even show themselves for months, at times even years. But when they become known, it’s because whatever they were joining has failed catastrophically. This guy probably wanted to show that he is brave enough to balance on these structures! We don’t know if he felt sweat dripping off from his forehead, but we surely are fretting after seeing this photograph.