This was posted here on a blog: http://www.davidgrant.ca/taqueria_chilos#comment-8469 in reply to a restaurant entry for a restaurant called Chilo's. There was one comment regarding a new location in Yaletown and this relates to that.
I thought of "old goat" too, but I've noticed the young Mexicans around here all call each other "cabrón", whereas "old goat" implies that this is an older guy.
I don't think a young man would ever call another young man a "horny old goat" - certainly not around here. "dog" would be OK, though - or maybe "you dog".