Yes, I agree with your point. When you're at an event with tens of people, you can look around and see who in attendance. All youngish tech guys? Great, let's

Yes, I agree with your point. When you're at an event with tens of people, you can look around and see who in attendance. All youngish tech guys? Great, let's push the boundary for stupid humor. That's an acceptable judgment, although I personally would still keep it professional. It's an understandable assessment. If, though, there are hundreds (thousands?) in attendance then prudence would suggest that you raise the floor of acceptability. The lowest common denominating factor has gone way down -- that people here all breathe air and want to see hackathon projects is about all you can safely assume. To come out and jerk off with your phone on stage is very poor judgment and not at all calibrated with the audience. Some things do not need to be explicitly spelled out, and it is not negligence on the part of the presenters to expect people getting up to speak publicly to exercise a basic level of judgment. The conclusion, "I can't safely assume that everyone here will find this funny, or at least tolerable," is not difficult to arrive at given the circumstances presented.