meaning "a goner, person or thing already doomed or destroyed" is recorded by 1987, perhaps from notion of computer circuits being "fried," and with unconscious echoes of earlier fig. phrase to be had on toast (1886) "to be served up for eating." Toaster in the electrical appliance sense first recorded 1913. Toasty "warm and comfortable" is recorded from 1890.
"a call to drink to someone's health," 1700 (but said by Steele, 1709, to date to the reign of Charles II), originally referring to the beautiful or popular woman whose health is proposed and drunk, from the use of spiced toast to flavor drink, the lady regarded as figuratively adding piquancy to the
wine in which her health was drunk. The verb meaning "to propose or drink a toast" also is first recorded 1700. This probably is the source of the Jamaican and U.S. black word meaning "extemporaneous narrative poem or rap" (1962).