The
root of the word is "sign", as in pronouncing or interpreting "signs" of the future or important spiritual symbols. This must be related to African or Afro-
American religious and spiritual practices involving the serious disucssion of divine signs and their meanings.
In a more general sense, if someone is
said to be "signifyin"", it may mean that they are taking themselves to seriously by holding forth on
deep portentious subjects in a self-important manner.
One might be describing pretentious intellectualizing or over-bearing preaching about matters which should make us humble by their mystery.
When asked to sign a timesheet at work, the
manager said, "Sure.. in Heberew or English ?"
On which a passing co-worker commented, "There he goes signifyin' again."
Since I happen to be Jewish, I
know exactly what he meant.