Lie like a rock

[bmo]

What is "lie like a rock?" Not moving anywhere?

[Tdol]

I don't know if it's an American idiom, but I haven't heard it. However, I go for that as the meaning.

[bmo]

Very few listings on the Internet, here is one:

"behind my back! He then said, "You guys lie like a rock! That's the
worst I've heard!" He continued, "I'm not dumb! You think I ...
travelsucks.com/bbs/ptopic648.html - 75k - Cached - Similar pages"

I heard it on the radio.

Thanks.

BMO