A set of Czech words can take the suffix -s representing deleted auxiliary verb jsi (2nd person). For instance, "To je dobře, že jsi přišel." ("It is good that you came.") can be shortened to "To je dobře, žes přišel."
These words are only slightly colloquial if at all. Moreover, the reflexive pronouns ses, sis were constructed the same way but are perfectly standard while the alternative jsi se, jsi si is poor style. ses is distinguished from se by the 2nd person and by the singular number in tag (
P7-X4----------). Similarly, kdos is tagged
PKM-1--2------- while kdo (who) is tagged
PKM-1----------. žes is tagged
J,-S---2------- while že (that) is tagged
J,-------------. It is questionable whether it is a good solution to let tags of various classes sometimes indicate the person and sometimes not. Nevertheless, the current morphological analyzer behaves so, and the approach should be extended to words not covered by the analyzer (e.g. cos, kdys).