I believe the West Indies vs South Africa cricket series is for only three tests. The first test was drawn and the second was won by South Africa. Yet on Betfair you can currently lay South Africa winning the series 3-0, the lay price being $11.

If it is only a three test series, then to my way of thinking it is impossible to lose???

I think they have 4 test series over in the West Indies.

Yep. Just checked. There's 4 tests.