Best definition
incredible randomness, weridness, something that doesn’t make sense or that can’t be properly explained, or a series of such events.
Example 1:

In the anime FLCL, some monsters pop out a people’s heads, there’s some space-chick on a Vespa, there’s a giant iron in the middle of town, they battle monsters with guitars; warbleflyff ensues.

Example 2:

Jimbo: So yeah, basically we found out that if you jump out of a humvee in mid-air you can activate your parachute and fly to saftely. So we attached C4 to it and drove it off a cliff over the enemy base, jumped out and pulled the chute.

Chuck: That’s awesome.

Jimbo: The enemy shot us down with a Scud.

Chuck: Warbleflyff.