So, Friend's welcome to the very first orkut trick.

Step1: Open scrapbook

Step2: Write [i] and submit it, an invisible scrap will b send

Note: Don't Write Anything Else [i]
You can try these various combinations also if u want to send a big no of invisible scraps, as after your few submissions it will start displaying the message "message sent too recently". So try these combinations out:

And just keep on increasing it will continue no limits...

One more method

Enter &#3021 no space b/w the symbol and number, blank scrap will be send.