How to remove smudges from the Nintendo DS Lite using cooking oil! *

A friend of mine asked for me for tips on how to remove smudges from his brand new Nintendo DS Lite. The following was the conversation, which happened in IM. Just in case you are dumb, I'm J and I did my best translating the conversation from Manglish to jolly good England, I mean English:

W: Hey!
W: How come there are so many smudges on my NDSL
W: How do I clean it?
J: Just pour water over it
J: The smudges will come off
W: F*ck you
J: Well, a better way would be to take a piece of cloth, dip it in cooking oil and wipe the NDSL
J: That will clear up all the smudges
J: And it will make the NDSL shinier
W: !!
J: Yup
J: It's a recommended practice
J: Try Googling it: "Cooking oil" + "Nintendo DS Lite"
W: Cooking oil...the one used in cooking?
J: Yup
W: You have to teach me this later**
J: Just dip the piece of cloth in cooking oil and wipe your NDSL with it
W: This won't damage my NDSL?
J: Nope
J: It's not water
J: Water + NDSL = Fried
J: Cooking oil + NDSL = Damn Shiny
W: But wouldn't it feel oily?
J: Nah... it's okay. Because after that you wipe it with a clean cloth.
W: Please teach me how..
J: Bring some cooking oil later
J: And please make sure it's not used.
W: Where do I get cooking oil?
W: Do I get it at Carrefour?
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** I had an appointment with this guy and his girlfriend later that day for dinner
* This was a prank on that guy! DO NOT USE COOKING OIL ON YOUR NINTENDO DS LITE!