smuggling

a  policeman  patrolling  always  found  one  truck  passing  across the  border  every  day,  he  would  stop  him , check  the  whole  truck  inside  out, but  never  found  anything  to  catch  him, one  day  the  guard  asked  him to  tell him what  did  he  do   carrying  nothing  in the  truck  , the  truck  driver  in a  friendly  manner  told  him he  was in  smuggling, smuggling  what, the  driver   wrote  down on a  piece  of  paper  and handed  him it, to  open it  after   he  had  gone, in the  paper  was  scrawled  , he  was  smuggling  trucks