Where wolf's ears are, wolf's teeth are near.. - Völsunga saga
Like the updated quote of 'loose lips sink ships"
I think they both apply to knowing who is listening in. Plot and intrigue during the Viking times and earlier times were mostly of an internal nature of an insider working for themselves or for someone else. When you find the listening wolf ears it is prudent to be ready and prepared for the wolf.
Today there are so many wolves at the doorsteps it is hard to protect oneself from them.
Yep, exactly like the loose lips/sinking ships phrase. I think maybe people get so used to putting everything out there that they forget to apply a filter when it's required. They just blurt stuff out without care as to who may be within earshot, or more to the point post on facetwit and twitbook without a care as to who may see the post. My oldest brother is like that...It's so ridiculous.