Slacked rhymes with:
blacked, lacked, abstract, act, attacked, attract, backed, blacked, bracht, counterattacked, cracked, detract, diffract, distract, enact, exact, extract, fact, hacked, impact, inexact, intact, interact, jacked, kracht, lacked, medfact, overreact, packed, pact, pracht, protract, racked, react, redact, reenact, repacked, retract, sacked, schacht, smacked, snacked, stacked, subtract, tacked, tact, tracht, tracked, tract, transact, unpacked, whacked, wracked
Slacked sounds like:
salcedo, salcido, salgado, scalzitti, schlecht, schlicht, schlict, select, selected, shellshocked, shelstad, silcott, silicate, silkwood, silliest, skylight, slaght, slashed, slechta, sleekest, sleight, sliced, slicked, slickest, slight, slighted, slogged, slowest, slugged, slushayete, socialist, socialized, sociologist, solicit, solicited, solicitude, soloist, squelched, squillacote, sulked