Examples:
https://bitcointalk.org/index.php?topic=178336 > bta.lk/thread/178336 / bta.lk/t/178336
https://bitcointalk.org/index.php?action=profile;u=3 > bta.lk/user/3 / bta.lk/u/3
https://bitcointalk.org/index.php?topic=2162.msg28302#msg28302 > bta.lk/thread/2162.msg28302#msg28302 / bta.lk/t/2162.msg28302#msg28302
Discussion thread: bta.lk/t/unofficial-bitcointalk-link-shortener