A friend of mine went to uni in Hull, he and everyone on his course were out-of-towners so not always totally abreast of local lingo.
On his way to college he'd pass a line of boarded up terraced houses covered in grafitti, including frequent use of the phrase 'Yeb off'. Thinking it was local slang he'd tell people on his course to yeb off, and soon they were all telling each other to yeb off.
Then one day as passed the boarded up houses he say a guy come out one of the buildings, nail the door shut, write 'Y.E.B. Off' on it and get into a Yorkshire Electricity Board van.