TAIPEI, July 13 -- Concertgoers at Taiwanese group Mayday's concert last night got a surprise bonus: an appearance of the group F4, singing their most famous hit Meteor Rain.

ET Today reported that last night was Mayday's Taipei Arena stop and it also became the first time F4 had reunited in 12 years.

More than 40,000 fans were treated to this unexpected show.

The last time the F4 members had appeared together was China's 2013 Spring Festival Gala.

Mayday had apparently attempted to invite the group as guests two years ago, but busy schedules prevented it from happening.

Besides Meteor Shower, F4 and Mayday also performed the latter's The Song of Laughter and Forgetting.

Will there be a possible group concert happening sometime? Aft...