Rolling along.

DW is a master at rolling.  Put him down in the middle of the room, turn your back, and he's managed to tumble into trouble.  Here he is trapped under his play gym:

And here he is trapped under the train table:

Notice how I like to take snapshots before rescuing him.

Now, this sort of thing would never happen with a first child.  For a first child, when they start moving and rolling, you remove all obstacles from your home, including coffee tables and other useless furniture, that might impede your little one.  You watch them like a hawk with your video camera as they barrel roll around your meticulously clean floors.  

For second kids, that obstructive coffee table might get pushed over a few inches, but you are sure as heck not moving it out of the living room like you did for #1.  And you are too busy dealing with toddler meltdowns now to notice #2 chewing on non-infant approved toys and sampling crushed up goldfish crackers in the carpet.  You are just going to hope this kid is a quick learner about how to survive the jungle.