Boy, do I wish I had been here, at the 10th Anniversary of the Montreal Expos:
This is 1978, so Youppi was not yet the mascot of the Expos. Instead, it was Souki, who Wikipedia describes as "a variation of the popular mascot of the New York Mets…with one difference." Souki had "odd antennas sticking out the sides of his head" (though I can't quite see them in these pictures).
Antennae or not, seeing Souki conduct the "Expos musical theme" would have been fantastic. As would have seeing Gary Carter, Steve Rogers, Warren Cromartie, and others play the trumpet and drums with the Montreal Symphony Orchestra. And don't forget the wine and cheese tasting!
Those Montrealers really know how to throw a party.