Photo courtesy of David Surovec.
Yes, during Czech Republic extreme metal warriors GUTALAX's set at BRUTAL ASSAULT 2019, chemical toilets were crowd surfed.
It is seriously doubtful that there was any human waste in the toilet and other than fans crowdsurfing, the toilet was unoccupied.
FROM METAL MILITIA:
During the special show, called by no coincidence the "Toi Toi Show", which GUTALAX held today at the Czech festival Brutal Assault 2019, Toi Toi chemical toilets also appeared on stage, one of which launched into an internship diving followed by the classic crowd surfing tour: