Is this some sort of satire at the futility of explaining fully a highly technical subject without the technical jargon? A non technical user is not going to want to absorb that laborious descriptive setup just so they can understand the algorithmic details of a process which has no relevancy to any other part of their life.

Here is the explanation as requested, but (a little bit) shorter:

"An SQL injection is when user input (meaning what you would type into facebook chat, for example) gets run as computer code. So, for example, an untrusted person can reprogram facebook to do what it wants."