Here was a recent "unforeseen" delay...
We were about ready to push and I called clearance to give them a heads up to start working on a release time to our destination airport. They came back and said that the destination airport had issued a ground stop due to weather and it would be in effect for 90 minutes.
We had already accepted a 2 hour extension and were going to be using the majority of it, but this ground stop would mean that we would land about 75 minutes past the end of our extension. At that point, we were at the gate, the door was open, and the jetbridge was connected. We knew of the delay, and in our opinion, it was no longer "unforeseen". We could clearly see that if we pushed, we would land well after our extension ran out.
The company's version of unforeseen and ours is evidently very different, as they said to just ignore the ground stop and push...thus making any further delays unforeseen and we could complete the trip.