Prepare to be shocked by these 15 controversial billboards

The ancient ancestor of the pop-up ad, billboards can snap us out of a 100-yard road-trip stare or a fascinating family conversation with humor, weirdness or very sexy torsos — much like this recent edgy billboard in California. And that got us thinking. Yes, we should probably be watching the road, but billboards remain effectively eye-catching. (Sorry about the back bumper, car in front of us.) Maybe it’s the singular one strong image/one strong message format; maybe it’s because anything looming 30 feet in the air in our peripheral vision demands our brain to react. (“Not a giant! Keep driving. Wait, are those boobs?”) In the interest of public safety, here are 15 of the most shocking billboards to gawk at while not operating heavy machinery.

Check out the msnNOW.com homepage to read more trending stories.