Whacker rhymes with:
wacker, acker, aker, akre, attacker, backer, bakker, blacker, bracher, bracker, cracker, hacker, lacher, lacquer, macher, makar, packer, racker, sacher, schacher, slacker, stacker, tacker, thacher, thacker, thakkar, tracker, vanacker, wacker, zacher
Whacker sounds like:
wacker, wagar, wager, wascher, washer, wasser, wazir, weaker, wecker, weckesser, weger, weicker, weiker, weiser, weishaar, weisser, weizsaecker, wesker, wesray, which're, whicker, whisker, whizzer, wicker, wickizer, wickware, wickwire, wicor, wieser, wigger, wiker, wiser, wisher, wisor, wisser, wyser