It's common slang for a huge 18-wheeler
... log book 
- it's a diary for truckers/one of the things they check at the chicken coops (4... [DOC] [TLE] Appendix:Glossary of truck terminology - Wiktionary [PAR] ... that discharges its load from the bottom, usually gravel; big wheel man : a 
trucker .... dropped); lot lizard : Trucker slang for prostitutes who hang out at truck 
stops.