Especially when the firework in question is a 10" mortar:

A 38-year-old suburban man allegedly admitted to police he drank 10 beers before lighting a commercial firework inside his home, blowing up the house and seriously burning himself and a female companion.
...
"Apparently, he thought he would light it, was kind of goofing around, and figured he could put it out," [Pat Barry, spokesman for the Will County sheriff's department, said.]

The man was wrong.

The device exploded seconds after being lit, blowing out a wall and every window in the home and setting it on fire. Neighbors heard the blast, called 911 and rushed to the scene.

Yet another Darwin near-miss. And I want to know where in the world there's a flea market that carries firework mortars nearly a foot across. I got some birthday money I need to spend...