ham (n.1) Look up ham at Dictionary.com
"meat of a hog's hind leg used for food," 1630s, from Old English hamm "hollow or bend of the knee," from Proto-Germanic *hamma- (cognates: Old Norse höm, Middle Low German, Middle Dutch hamme, Old High German hamma), from PIE *konemo- "shin bone" (cognates: Greek kneme "calf of the leg," Old Irish cnaim "bone"). Ham-fisted (1928) was originally in reference to pilots who were heavy on the controls, as was ham-handed (by 1918). With hammen ifalden "with folded hams" was a Middle English way of saying "kneeling."
ham (n.2) Look up ham at Dictionary.com
"overacting inferior performer," 1882, American English, apparently a shortening of hamfatter (1880) "actor of low grade," said since at least 1889 to be from an old minstrel show song, "The Ham-fat Man" (1863). The song, a black-face number, has nothing to do with acting, so the connection must be with the quality of acting in minstrel shows, where the song was popular. Ham also had a sports slang sense of "incompetent pugilist" circa 1888, perhaps from ham-fisted. The notion of "amateurish" led to the sense of "amateur radio operator" (1919). The verb in the performance sense is first recorded 1933. As an adjective in this sense by 1935.