That’s my personal favorite. Especially since I teach freshman comp. 
As soon as I saw this thread, I thought; “Kid’s Book”.
Thanks for stopping by, you guys. Thanks for breaking my cow lamp.
Strong Bad, Batman, what are you doing in my room?
“E-mail is like a prison with no walls. And no toilet.”
My favorite ones would have to be
Different Town- “Daaaaa… I’m forever youurr giirlll…”
Techno- “And there’s always some kinda high pitched sound, y’know like a siren that’s like…”
Japanese cartoon- “DOOOUUBLEE DEUUUCEEEEEE!!”
Kind of cool- “Excuse me, ma’am, but could you help an ol’ wintergreeennn gather his spectacles?” (The look on Strong Mad’s face is priceless.)
Guitar, I love this one becuase I happen to play the bass. “And then Strong Mad comes in on his bass and it’s like dow dow dow dow dow dow DOW dow dow dow dow dow dow…”
Trogdor- “CONSUMATE V’s I SAID CONSUMATE! Jeez… guy wouldn’t know majesty if it bit him in the face…” “That happened once!”
Mile- “How did you- what’s your secret?” “The Cheat, he’s a millionaire! HOORAY FOR THE CHEAT!”
Kids’ book- “Some people are about to be run over! Frankie has about five seconds.”
And another one, which I cannot remember started out like this “And then Trogdor smote the Kerrek, and all was laid to burnination.”
And another one I don’t remember had an easter egg in it, parodying the Brothers Chaps first Homestar book. “Strong Bad did a jig while holding all the grapes, and the cheat learned to FLY!”
Property of ones is good…but the two best IMHO are:
Bird – “Behing the back, around the world!” – priceless
SBE-mail22 – “Just say screw all ya’all. It will work, trust me” – gold, solid gold.
I don’t remember the names, but I really liked the series of e-mails which involved him trashing his old computer and getting the new one.
You’re looking for invisibility - at least that’s the one where he gets his new computer.
[strongbad]
*For Behold… the 386! A spectacle of graphics and sound! *
[/strongbad]
It all started innocently enough. Strong Bad was answering an e-mail about gimmicks, when his computer inexplicably blew up. He was forced to use The Cheat’s iMac to explain a weird dream (“Your computer has too much computer in it, and not enough typewriter”). He was able to get the old girl working again, but it didn’t work well at first. It ended up deleting an e-mail from two sisters, but was able to get it up and running to explain his guitar skills, how to take care of the office dullard, what his voice sounds like when he inhales helium, and the Propety of Ones (“A one that isn’t cold is scarcely a one at all”). He then took a well-deserved vacation, and returned with a new computer, much to the Tandy’s dismay (“Remember the duck pond?”) He used it first to comment on invisibility (“Survey says…you’re an idiot!”)
The Video Games one. I even made an image macro for “Your head a splode” (with the classic “Story of Ricky” screengrab that the Daily Show helped make famous).
I gotta go with an oldie that really cracked me up when I first saw it: old number seven, Halloweener.
I think it’s the way Homestar says, “I’m a bell.”