todate() function behaviour

Hi,
I had faced a scenario when working on todate function.
todate("15-coversion-2015") gave output as 10/19/1618.
todate("15-czurich-2015") gave output as 10/19/1618.
But, the below stuff which is also some junk is expected to give same output as above but gave the below output:

todate("15-madh-2015") -> 5/15/2015,
todate("15-junk-2015") -> 6/15/2015.

Please clarify if the above is expected behaviour. Thanks for your inputs.

OriginalPostID-264637