DULUTH, Minn. — A somewhat overexposed billboard designed to get people talking about colon health has been censored by the agency that put it up.

The billboard in Duluth says: "Cover your butt! Get a colonoscopy."

It shows a portion of a man's buttocks with his pants slightly down.

WDIO-TV reports (http://bit.ly/11eTJ7a ) that the Minnesota Department of Health recently put a white box in the center of the ad, to cover a portion of the man's exposed buttocks. Department spokesman Scott Smith says some people complained the ad was offensive.

He says the box was "an experiment to see if it keeps the conversation going."

Smith says similar billboards are elsewhere in the state, but the Duluth one is the only one that has been censored.