On Sunday night, Wayne bailed on a concert in Rochester, New York, at the last minute. He WAS there, but according to (the annoying gossip blog) PerezHilton.com he canceled it because "the sound system was not up to his standards".

The 8,000 people that were at that show were offered full refunds. LUDACRIS had already performed, so basically, they got to see him for free.)

The following night, on Monday, Wayne apparently threw another DIVA-like fit . . . disappointing around 20,000 fans at an event called Monster Jam in Boston.

Again, he WAS there. And this time, he didn't even get to check out the venue's sound system . . . because he REFUSED to pass through security (specifically, a metal detector) in order to enter the venue.

There's a lot of gossip out there. Some reports say Wayne was upset HIS security detail was blocked from entering after they set off the metal detectors . . . and others say Wayne was just drunk and throwing a tantrum. Either way, he didn't go on. JAY-Z . . . who was also performing at the event with DJ AM . . . extended his set in an effort to appease the crowd.