The Smart car of the future. Scientists are currently working on a way to contain human flatulence for use in smaller, more efficient vehicles. The prototype tested has only been able to travel a few feet due to limited amounts of flatulence available per person, but the experts are also working on a way to clone and condense human farts so that one fart can become many more, thus increasing the volume available per person. People will be encouraged to consume large amounts of fiber (especially Fiber Bars) and carbonated water and drinks to increase their gas production. Instead of plugging your car into an outlet and wasting electricity, or buying the more traditional, expensive type of gas, you would fart directly into a tube that leads into your car's "gas tank", which will have a self-sealing valve after each deposit.
The Fart Car will prove to be a valuable means of transportation in the future, as farts are free and we will no longer be required to depend on foreign oil resources. The future is looking brighter, if not a bit stinkier.
The thing that appears above your head when you think to yourself, either silently or out loud, "WWJD?"
When you suddenly have a thought of remorse or guilt, the moment the lighbulb appears above your head, (only this time with a vision of Jesus in it with his hands held out and that puppy-dog look in his eyes...) that makes you stop and rethink your actions and the repercussions of those actions.
Dude: "Hmmm... I probably shouldn't have pocketed that $20 that just fell outta that lil' ol' lady's purse...."
(Result: Jesus appears in a lightbulb above wrong-doer's head).