a stereo-type made from americans that think we say it all the time. But when actually used, it used to make sure the listner comprehends or is even still listening, also a short way of asking after an opinion if the listner agrees with you or not.
BOB: "americans think we say "eh" all the time did you know that eh?"
SUE: Really? like how they think we live in igloo's and ride around on dog sleds aswell?