During the very fist chapter 'Underground Cemetary' you'll be able to spot a few chances to do this without having to set it up yourself.
About half way up to the top there will be your first possibiliy (and there'll be at least one more on your way to the top). Just pay attention to 5 blocks sticking next to each other in a line with an empty spot next to them in line.
Push = achievement (it's almost like giving birth ;p ).