It's common slang for a huge 18-wheeler
In Northern
... [DOC] [TLE] List of CB slang - Wikipedia [PAR] CB slang is the distinctive anti-language, argot or cant which developed among 
users of ... CB and its distinctive language started in the USA but was then 
exported to other countries ... "Wall-to-wall bears": A large number of police 
vehicles, especially when on a chase.