Hey guys, this can hardly be called a guide, but more of a fun tip.
Whenever I am on my bank alt scanning the Auction House etc, I post in trade
"Selling jokes bound to make you laugh from a wide variety and genre range! 15 gold per joke - PST!"
Then all you do is before hand is get a selection of jokes (google is your friend) - good jokes no the stupid why did the chicken cross the road kind of things, and put them in a txt file. Separate them into different genres such as Classic, Movie related, Adult, WoW Related, etc and then when someone whispers you ask them which genre they want.
It's up to you if you believe this works or not but it actually does - sure it's not a solid income by far but it is a lazy way to earn a quick buck or two while stuck on a bank alt crafting or scanning.