Speaker Relative Adjectives

I have been toying with the idea of putting the following system in my
conconlang: adjectives whose meaning changes based on the traits of the
speaker.  e.g:
wer-age
werkU-in the same age group as the  speaker.  when a  child says 'werkU' it
would mean 'young'.  from an adult speaker it would be 'old' or adult,
depending on context.
wervIp-not belonging to the same age group.  again with a child saying this it
would mean not young or (usually) old. from someone of middle age this term
could refer to all of those who are not middle aged, including children and
the elderly
werhoch-the percieved opposite of the trait.  from a child this would
absolutely mean old or perhaps very old.  from someone of middle age, however,
the context would have to explain whether the speaker is relatively young or
old.

perhaps this system will not work out as well as I have planned, but I also
plan to forbid it in speaker-unknown situations.  does any such system already
exist in a natlang?
pacs precs
Joe Mondello