Imperative/subjunctive.

[John Myhill]

The particular example Tom mentioned is a completely normal usage in Black
English--the form is typical, the habitual meaning is typical. For African
Americans, such a usage is not only not unusual, it is the only way to
say this (the -s inflection can come or go, regardless of the person/number
of the subject, but the invariant BE is always there).Sociolinguists
(e.g. Labov) have been talking about this a lot for the last 30 years.
I don't know the personal background of the speaker Tom heard, but my first
guess at least would be that this is either Black English or a borrowing
from Black English.     John Myhill