At a great rate; immoderately.

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1856.  Then she laughed fit to kill. I did n’t ’spicion p’raps what she was at, so I gin her the most fattest one of ’em.—Knick Mag., xlviii. 433 (Oct.).

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1862.  

        ’T was Concord Bridge a talkin’ off to kill
With the Stone Spike thet ’s druv thru Bunker’s Hill.
Lowell, ‘Biglow Papers,’ 2nd Series, No. 2.    

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1908.  I snapped the whip over old Nell’s back and drove right on to Goshen, and Abram jest set back and laughed fit to kill.—Eliza C. Hall, ‘Aunt Jane of Kentucky,’ p. 165.

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