Sincere US indie types Band of Horses (dissapointingly, this isn't to be taken literally) recently surprised a couple of fans with a live performance at their wedding, which was taking place coincidentally on the same weekend the band were playing a nearby festival. Nobody threw wee in the air at this performance though.

"Njal proposed to Elin at the Band of Horses show in Oslo earlier this
year. When the Bride and Groom heard that BoH was to play a festival in
Tromso on the same day of their wedding, they contacted the band and
told them their story. With all the coincidences surrounding the
wedding, the band said, 'What the hell' and decided to surprise the
couple."