Similar to narzos' counter-example of the Pentecost would be similar, relatively modern experiences of Catholic missionaries with
xenoglossia in South America. In various dubiously and/or partially documented instances thousands of native people witnessed Western priests, uneducated in the local tongue, speaking to them in their own language.
Other examples from Catholicism might include any of the various apparitions of
Mary. A good specific would be the apparitions of Mary at
Fatima and the corresponding "
Miracle of the Sun," (13 October 1917) in which thousands claimed to see the sun dance, glow brighter, stop or such. The event has been tagged - depending on who you ask - as proof of the legitimacy of the prophesies handed down at Fatima, and as yet another example of mass
hallucinations experienced many times in the early part of the 20th century by European crowds claiming to witness miraculous appearances of Mary.
Tom Robbins explores the miracle/hallucination argument in passing in his hysterical
Fierce Invalids Home from Hot Climates.