Gustavus rhymes with:
mischievous, beavis, bodhisattvas, canvas, canvass, chivas, corvus, covas, crevice, davis, davis', disservice, gervase, grievous, holvis, holvis', jarvis, mischievous, navas, nervous, novice, pelvis, provus, service, synovus
Gustavus sounds like:
gadbois, gadhafi's, goodbyes, guidebook, guidebooks