It's apparently an in game pastiche of internet forums, complete with characters based on the type of users you encounter online. Pretty neat way to give tips:
http://www.mariowiki.com/D.I.Y._Forum#Topics
http://www.mariowiki.com/D.I.Y._Forum#Topics
'T-shirts: Ok, so the game is always looking for all the triggers, right? Then it executes any action, then goes back to looking for triggers? That's kind of like my life...
a + b: Huh. Mine, too... Also, I think I understand AI way better now.
miniMAL: I'm sooooo bad at drawing! Why did I ever think I could be a comic artist?
andboom: Did you forget that the Comic MakerMatic has stamps? Who needs drawing ability with those around?
D.I.Why: Why DID you want to be a comic artist, miniMAL?
VROOM: Just heard a rumor that Jimmy T. and Mona of Diamond Software used to work at WarioWare, Inc.!
blobmob: for real? why'd they leave? was there a big fight? lol
D.I.Why: I heard Wario never did any work! I hear he's up to something now, though…
D.I.Why: I heard that almost all games now are made with the MakerMatic engine!
MeOWza: I think everything in D.I.Y. Shop is, yeah.
blobmob: crygor must be wearing a lab coat made of money lol
flour: Diamond Software makes THE best games! Especially Mona's stuff, for some reason. Her titles are always big fun for me!
Javier: The company president is a guy named Manager Joe.
Phonee: Wow! Leave it to Javier to have all the obscure trivia!
AAAaaah: A friend made this AWESOME game for my birthday where I get to pop a party popper! He's the best!
D.I.Why: Touching. I might cry.
T-shirts: Don't listen to D.I.Why. That's a good friend!
AAAaaah: I want to get into game making, but I just… can't. Why can't games just make themselves?!
VROOM: Dude, the whole point is to be creative—so create!
KAGE: or, y'know, import some diamond software games and change 'em around![]()
T-shirts: Remember that the Game Blender keeps speeding things up. If you can't beat your game at the highest speed, adjust it.
KAGE: cue flame war about noobs needing to learn to play! popcorn, anyone?![]()
John Sun: If you change instruments, be sure to play the phrase back so you hear what it really sounds like.
Phonee: Captain Obvious reporting for duty! BREAKING NEWS: water is wet! Film at 11!
foe-vine: In D.I.Y Showcase on the Wii, how many games can you send from the DS?
Smoth: 72!!!!!! HYPE TRAIN!!!!!!!!
123POP!: All aboard! You could use it as extra storage when your D.I.Y Shop fills up!