Find an idea. Decide if you want your participants to sing and dance, or just dance.
Decide on music. Remember that your song is going to be broadcast in a public area. Select a song that is appropriate and has the beat and timing you need for your dance.
Decide on a location. Find a large, open public area with lots of space for spectators. Make sure your group has enough room to dance. Decide the day and time of your musical number.
Invite people to participate. Most people hear about spontaneous musical numbers by word of mouth or text message. Decide if you want to formally invite participants through email or invitations. Although a larger group is difficult to teach the dance to, larger numbers can create an impressive dance number.
Rehearse. Arrange for your participants to rehearse in a school gym, public park, football field or other large space to learn and practice your musical number. Know your dance number beforehand. Teach the number to a few others and position them throughout the crowd to help with instructions.
Check local laws. Make sure your musical number does not violate any laws or city ordinances. Work with community police and officials before organizing your event.