If you're a sweepstakes fan, a "surprize" is more than just a misspelled word. Surprizes are slang for sweepstakes prizes that arrive unexpectedly, without any advance notice.
Surprizes usually aren't the biggest prizes you can win. After all, affidavits are required for any sweepstakes prizes worth more than $600 (and are often requested even for smaller prizes). But having a surprize show up at your doorstep is a lot of fun, kind of like Christmas any day of the year.
Surprize is pronounced just like "surprise."
The UPS man showed up today bearing a surprize - a selection of books from one of my favorite authors. Yippee!