This billboard left 'em blushing.

A spelling error on a digital billboard ad for a Midwest school system turned "public schools" into "pubic schools."

The Blue Waters Group, a public relations firm, is taking full responsibility for the error, acknowledging that the mistake was apparently overlooked by four people on staff who did not identify the missing “L” before approving the message. 

“I feel terrible. It’s a mistake we made and we’re guilty of it,” said Patrick Strickler, president of Blue Waters. The misspelled billboard, to promote the South Bend, Ind., school system, went up Thursday and was not corrected until Monday. It was located near the intersection of Ironwood and State Road 23, visible to the thousands of drivers who use the road daily. 

Two of those drivers were South Bend residents Lee MacMillan and his wife, who took a picture of the sign and uploaded it to Facebook. MacMillan also forwarded the picture to his neighbor, South Bend Schools Superintendent Jim Kapsa. "We jumped on it and immediately had it taken down by Burkhart [the billboard company]," said Strickler. 

The corrected message now reads, "15 best things about our public schools."