No ambush teaching, please! The participants should always have the informed consent whether they want to participate, and they should know the conditions of involvement.
Treat each other with respect. Photo by William Fortunato
People come to festivals to have an “experience”. Festival attendance is a voluntary activity in which individuals allocate time, financial resources and plan well in advance. This is their time, and they chose to be there at that moment. Your project should respect this.
The organizers should inform potential participants about the project. Information is communicated through channels appropriate to the nature and needs of the specific target groups. They should be able to make an informed choice. Participation is voluntary in the project.
Try to think of how you could make it less of an effort for the participants to take part but great fun instead, without losing focus on your cause or being silly.