Evtimov et al., arXiv.org In a test of a right-turn sign, a mask that filled in the arrow on the sign resulted in a 100 percent misclassification rate.

This stop sign has been covered by a full-size replica that includes subtle camo marks. This was 100 percent effective at fooling their machine into thinking it was also a 45mph speed limit sign.

Portlanders apparently upset with the direction of the local housing market are slapping "no Californians" stickers on For Sale signs in the city, real estate agents say.