Depends on the situation, usually on campus, I rock up and say something along the lines of “Ay bro smile you on camera” and point at one of the many security cams. Or if they are clearly drunk in public usually I just stay with them and ask if they have a parent or friend that can pick them up or get them or call an Uber and pay for it. General life though a lot of the time I do nothing unless they actively are asking for help.