No one thinks its funny that a woman was injured. What causes the humor to kick in is the irony of a "manhole" "Cover" being "Blown" causing an "explosion" in "San Francisco."
It's not terrorism despite what the man behind the curtain says. It was an accident. There is humor to be found in the wording associated with the incident.
If you really can't handle the dripping sarcasm found on this thread, I would suggest you avoid it for the time being.
This guy must surf analporn between wisecracks on FR!
And the explosion being described as sounding like "a big poof"...