I actually broke one of my DS's with that... (I've had three, now i have 2).
I was in an online game of metroid hunters. And after a few games, i was really into it... And then i started pressing really hard on the screen with my stick (you know, your really focused after a few online games...) And then i broke my touchscreen... Calibration didn't work and only like 1/4th of the touchscreen worked... But i still had 1 month of warranty on it so i traded it in!... And luckily, it got fixed! Thank god for Nintendo's customer-service!
So my tip for you: If you still have warranty on it, just break the screen by making scratches on the screen... Then say it just... Happened... or something! I dunno, make a bullshit story, just like i did! And you just get a brand-new one! I know mine was brand-new because i copied the serial-number on the back and they were different when i got the DS back!... But remember, ONLY if you still have warranty! 
... And if it's a DSphat, you might even get a Lite... However, i didn't! But that was like 1-1.5 years ago!
THE NETHERLANDS
