It sounds quite unlikely but that’s what they’re claiming here:
The closest I’ve seen to an all-school picnic during my time here was the one behind the library during the centennial celebration in October, 2012, more than 70 years after the earlier event. It was quite different from the rather sedate 1941 version. It was, in fact, mayhem. But it was great fun:
And it was followed by one of the most efficient clean-up operations I’ve been privileged to watch. The facilities staff was the unsung hero of the entire centennial.