What does this mean and where does it come from?

[chuckywang]

I see a lot of people have posted something like this:

Step 1) do something here
Step 2) ....
Step 3) PROFIT


What does this mean and how did it originate??

 

[Orsorum]

South Park - Gnomes

 

[loic2003]

It was the underpants gnomes of south park. They stole people's underpants and they had the following business plan:

Step 1)Steal Underpants
Step 2) ....
Step 3) Profit!

Funny episode...