When two people are in the cab of a pice of heavy equipment ie a tractor, and one person starts to perform oral pleasure to the operator of the pice of heavy equipment
Steve and Sarah went out on a tractordrive and Steve's father said he saw them cabslaggin on their way.
A girl who goes with a culchie in his tractor and does some saucy things with him in the cab. Or it can just be when she sits with him in the tractor while he works.