Backpacks rhymes with:
aipac's, compaq's, eastpac's, gopac's, midpac's, opax, tampax, westpac's, affymax, aftertax, aipac's, ajax, amtrak's, awacs, backtracks, blendax, borax, bushwhacks, buybacks, cadillac's, cadillacs, carjacks, climax, comebacks, compaq's, counterattacks, cutbacks, drawbacks, earwax, eastpac's, equifax, fairfax, filofax, flapjacks, flashbacks, florafax, fosamax, fullbacks, galax, givebacks, gopac's, greenback's, greenbacks, gunnysacks, halfbacks, halifax, haystacks, hemophiliacs, imax, imax', interfax, kickbacks, knickknacks, kodak's, leasebacks, leatherbacks, lilacs, lomax, macintax, maniacs, mesothorax, metathorax, microvax, midpac's, miramax, mullenax, nymphomaniacs, officemax, opax, overtax, paperbacks, parallax, paybacks, pentax, pontiac's, pontiacs, pricklebacks, pullbacks, qmax, quarterbacks, racetracks, razorback's, razorbacks, rollbacks, rothwax, setbacks, skipjack's, skipjacks, smokestacks, soundtracks, surtax, syntax, tampax, tarmacs, turbotax, weatherwax, westpac's, wisecracks, wolenzac's
Backpacks sounds like:
backpack, backups, bagpipes, bake-offs, bespeak, bespeaks, biceps, bishop's, bishops, bishops', bookshops, boskovich, bukavu's, bukovsky, busboys