One often hears native English speakers use constructs such as "where's my trousers" or (from this forum in another post) "where is my parents and mothers?"
Is that a case of spoken grammar differing from written grammar, a case of specific variants of English from different regional areas, or just a very frequent error in English (and given the frequency of occurrence are we bordering on a change in spoken grammar)?
The question is not about the "logical" aspects but more about actual usage.
** Edited on 2017/Feb/13: changed the question to focus on
's instead of
is form in spoken english **