Why turkey has the same name as Turkey
"to brown with heat," late 14c., from Old French toster "to toast or grill" (12c.), from Vulgar Latin *tostare (source of Italian tostare, Spanish tostar), frequentative of Latin torrere (past participle tostus) "to parch" (see terrain). Related: Toasted; toasting.
"to propose or drink a toast," 1700, from toast (n.1). This probably is the source of the Jamaican and U.S. black word meaning "extemporaneous narrative poem or rap" (1962). Related: Toasted; toasting.
"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 (n.2) to flavor drink, the lady regarded as figuratively adding piquancy to the wine in which her health was drunk.
"a toasted piece of bread," early 15c., from toast (v.1); slang 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 figurative phrase to be had on toast (1886) "to be served up for eating."
To talk or chant in the reggae music mode: not exactly toasting, it was a kind of primitive rapping, consisting mainly of new slang words and an occasional joke (1970s+ Musicians)