wisecrack (n.)

Old English wis "learned, sagacious, cunning; sane; prudent, discreet; experienced; having the power of discerning and judging rightly," from Proto-Germanic *wissaz (source also of Old Saxon, Old Frisian wis, Old Norse viss, Dutch wijs, German weise "wise"), from past-participle adjective *wittos of PIE root *weid- "to see" (hence "to know"). Modern slang meaning "aware, cunning" first attested 1896. Related to the source of Old English witan "to know, wit."

A wise man has no extensive knowledge; He who has extensive knowledge is not a wise man. [Lao-tzu, "Tao te Ching," c. 550 B.C.E.]

Wise man was in Old English. Wise guy is attested from 1896, American English; wise-ass (n.) by 1966, American English (probably a literal sense is intended by the phrase in the 1607 comedy "Westward Hoe" by Dekker and Webster). Wisenheimer, with mock German or Yiddish surname suffix, first recorded 1904.

mid-15c., "hard wafer," literally "that which cracks or breaks," agent noun from crack (v.). The specific application to a thin, hard or crisp biscuit is by 1739, mostly in American English; the meaning "instrument for crushing or cracking" is from 1630s (compare nut-cracker).

Coal-cracker is from 1853 of persons, 1857 of machinery that breaks up mined coal. The cracker-barrel (1861) full of soda-crackers for sale was such a common feature in the popular perception of country stores that the phrase came to be used by 1905 as an adjective, "emblematic of down-home ways and views."