Twitter is trademark of Twitter Inc. Twitter Inc. acquired twitter.rs, so they may be interested to start a lawsuit against you protect their brand. Drop the domain. Just my 2 paras.
I see no value in the domain there are much better hacks available in .rs (
personally I own 8 ) and sure thing Twitter might wanna protect their brand, a clear drop/delete... contact Loopia or whatever your registrar is to get it grace deleted asap..