Nebbish is a good one, meaning a nerd or loser.
Back in the 70s a friend of mine went to college in Hull. Everyone on his course was from out of town so in their first term a lot of the conversation was about the local slang and dialect they were hearing.
On his walk to college was a row of buildings being boarded up for demotion and spray painted on various bits of boarding was the phrase ‘Nyeb off’. So he introduced ‘Nyeb off’ into conversations and soon all his course mates were telling each other to nyeb off.
Then one morning he saw a guy come out of one of the buildings, nail the door shut, spray ‘NYEB off’ on it, then get into a North Yorkshire Electricity Board van.