WordNet (r) 3.0 (2006):

boxcars
    n 1: (usually plural) an expression used when two dice are
         thrown and both come up showing six spots

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "boxcars":
   L, Sexagesima, boxcar, dozen, duodecimo, eighty, eleven, fifteen,
   fifty, five and twenty, fortnight, forty, four and twenty,
   fourscore, fourscore and ten, fourteen, half a hundred, long dozen,
   ninety, nonagenarian, octogenarian, quindecennial, quindecim,
   quindecima, quindene, score, septuagenarian, seventy, sexagenarian,
   sexagenary, sexagesimo-quarto, sixteen, sixteenmo, sixty,
   sixty-four, sixty-fourmo, teens, thirteen, thirty-two,
   thirty-twomo, threescore, threescore and ten, twelve, twelvemo,
   twenty, twenty-five, twenty-four, twenty-fourmo, two dozen,
   two weeks, twoscore