Appeal To Popularity is an attempt to convince the opponent to change his argument in your favour because of the opinion of the majority.
This fallacy is similar to Bandwagon, but the difference is that bandwagon implies that dissidents will be social outcasts.
"Hardly anybody in the building likes children, so they're within their rights to evict families with children."
"So many people are lining up to see this movie; it must be good."