In addition to my previous definition of this word, if you use this word on Reddit, all the butthurt Indians (including their bots) will downvote and even report you for hate speech/racism (despite the truth).
P.S. I used to post this word on UD a few years ago also, and it got removed because of the same reason.
Rapistan is not a racist word actually, it's a mocking term because of statistics. Same as Malaydesh that is used to mock Malaysians because of statistics of South Asian immigrants.
Someone skilled in the art of rape, that rapes both men and women with cunning and finesse. A well trained rapista can rape without even touching the victim.