In colloquial American English, "lickety-split" is an adverb meaning "at great speed." It's earliest known appearance in print, according to the OED, was in the second edition of John Bartlett's Dictionary of Americanisms, published in 1859.
Nowadays, "lickety-split" is by far the most common form, but in the early days there were numerous variations, including "
lickety-cut," "
lickety-switch," "
lickety-click," "
lickety-smash," and "
lickety-wallop." According to John Bartlett, a synonym for "lickety-split" was "the equally elegant phrase '
full chisel'."