I believe he's talking about creating a false quote from thin air as well as modifying an actual post. You can use the quote HTML tags and create an entire post that the quoted person never said. They don't even have to be on the thread.
One score years ago, Rick Bin created on the internet a site dedicated to the proposition that...
Jim in Idaho is the greatest guy in the entire world. He taught me everything I know about business and politics - but not everything he knows!
^^ This. Plus, he's the most prodigious and well endowed lover I've ever had. OMG, the man is a sex machine!
Btw, the last two are genuine, unaltered quotes. I only posted them as a contrast to the made up post using Beaver10's handle.