Pardon my hubris.

The correct words are:

    An old man sat in the grandstand chair,
      Hay in his whiskers, grey in his hair,
      And his voice rang out on the sultry air,
      "I'm bettin' the roll on Roamer!

      "She was sired by Zev out in Arkansas.
      Her mother was cousin to Man o' War.
      She's broke every record that she's tried for.
      I'm bettin' the roll on Roamer!

      "I'm folding up when this race is run.
      The bookies are laying me thirty to one.
      It's a lead-pipe cinch I'm a son of a gun.
      I'm bettin' the roll on Roamer!

Chorus

      "Then I'll build a big city mansion
      And a summer home down by the sea,
      And I'll put the old mare on a pension,
      When she brings home the bacon to me.
"
      The jocks were dressed in their silks so gay.
      The crowd was immense that Memorial Day.
      "She'll win in a walk," they heard him say.
      "I'm bettin' the roll on Roamer."

      Then off they rode to the starting place,
      While thousands debated who'd win the race.
      You could read the words in the old man's face:
      "I'm bettin' the roll on Roamer."

      The crowd was still and the air was tense,
      And thousands were holding their breath in suspense.
      Came a voice as sharp as a picket fence:
      "I'm bettin' the roll on Roamer!

Chorus

      "Then I'll build that big city mansion,
      And that summer home down by the sea,
      And I'll put the old mare on a pension,
      When she brings home the bacon to me."

      The old man climbed to a higher spot.
      The barrier's sprung and they're off like a shot,
      With the old man yellin', believe it or not,
      "I'm bettin' the roll on Roamer.

      They passed the corner, Oh Lord, be kind,
      For Roamer is nearly a quarter behind.
      "That jockey must either be dumb or blind,
      And I'm bettin' the roll on Roamer."

      The crowd all yelled when they passed the line.
      They pulled in the stretch and the goin' was fine.
      "I thought I was rich but she slipped in a ditch,
      And I had all my roll on Roamer."

      "There may be a big city mansion,
      And there may be a home by the sea,
      And the mare may be put on a pension,
      But by somebody else beside me."