I suspect it is a different (and incorrect) spelling of "
λέμε", "we say", that is used for emphasis, in casual speech or slang. You'd say, for example:
-Καλά, η ταινία ήταν γαμάτη, λέμε!
I have no idea why the different spelling, though. It must be some slang variation, maybe someone else could help us out.