Mongobert LIKE concrete underpants! They never wear out, they easy to clean (use power washer once a week), they protect 'little Mongobert', and they make great conversation starter. Of course, Mongobert not ask ladies if they want to see his concrete underwear any more. Mongobert not like conversation that follows.
I've laughed about this off and on since it came out - not sure of the specific meaning of "wearing concrete underpants" either, but somehow I intuitively "get it" and it makes me laugh!
I agree about the hair, it looks like she's giving everyone the finger. I like the right brain left brain theory, too but I think there is a more simpler translation - "you may as well stop kissing my ass because i'm not receptive".