I have seen the below context
"Ishant Sharma removed Shane Watson with a ripper"
in Cricinfo. What does "ripper" mean in the cricket?
Its actually an Australian slang which means "Fantastic". In cricket the commentators use this word when a bowler bowls an unplayable ball to the batsmen.
Basically it is used for a delivery which is too good, almost unplayable and completely beats the batsman. Earlier it was used by Australian cricket. Then it became popular in whole cricketing world. It is same as Jaffa which is mostly called by English cricket.
"Ripper" has been an Australian term of delight ("What a Ripper!"; "You little Ripper! "; "Let 'er Rip") for many years now.
More analagous and quite common amongst country male folks :
" You bloody ripper ".
Which literally means 'Bloody bottler, you little beauty, fantastic.. ' or 'rip-snorter'.
I believe that the cricketing usage of the term 'ripper' might have begun out as a term used to refer to an excellent spinner's delivery, a ball with big turn for a spin bowler, (especially a legspinner) who can use the whole action of the wrist to impart maximum revolutions on the ball. Shane Warne, consequently, bowls a lot of "rippers" - http://www.espncricinfo.com/ci/content/story/239756.html
Over the ages, the term has gone onto a generalized form to now represent a really good delivery by a bowler that beats the batsman's defences.
Ripper in cricket commentary was introduced by the great Australian commentator Bill Lawry for an unplayable ball generally bowled by a spinner.