Origin: ME coking-stole, lit., toilet seat < ME coken < OIce kuka, to defecate: the instrument was orig. made like a toilet seat to heighten the indignity
See cucking stool in American Heritage Dictionary 4
cuck·ing stool
nounOrigin: Middle English cukking stol, from cukken, to defecate, of Scandinavian origin; see kakka- in Indo-European roots.