1784, lolly-pops "soft candy, coarse sweetmeat made of treacle and sugar, usually with butter and flour added," a word "of obscure formation" [OED]. The elements are perhaps related to loll (v.) "to dangle" (the tongue) + pop "a strike, slap." Or the first element may be northern dialectal lolly "the tongue." Figurative sense of something sweet but unsubstantial is by 1849. Meaning "hard candy on a stick" is from 1920s.