Slacker rhymes with:
blacker, lacher, lacquer, acker, aker, akre, attacker, backer, bakker, blacker, bracher, bracker, cracker, hacker, lacher, lacquer, macher, makar, packer, racker, sacher, schacher, stacker, tacker, thacher, thacker, thakkar, tracker, vanacker, wacker, whacker, zacher
Slacker sounds like:
salazar, salguero, salser, salzer, salzhauer, schlager, schleicher, schleiger, schlesser, schlicher, schlicker, schloesser, schlosser, seliger, selsor, selzer, silguero, slager, slasher, sleeker, slicer, slicker, sligar, sliger, sliker, slugger, slusher, slusser, sulcer, sulser, sulzer