Gergen's rhymes with:
jergens, juergens, jurgens, balbriggans, bargains, bennigan's, cardigans, copenhagen's, corrigan's, diegans, dorgan's, dougens, douggins, dragon's, dragons, feagans, flanigan's, flashguns, gilligan's, goggans, gorgons, hagans, hagens, hargens, higgens, hooligans, jergens, juergens, junghans, jurgens, kerrigan's, machineguns, megan's, michigan's, morgan's, morgans, mulligans, oregon's, organs, plagens, rattigan's, reagan's, reagans, reagans', regan's, shenanigans, siegan's, slobogin's, slogans, snapdragons, toboggans, vegans, volkswagen's, volkswagens, wagons, wiggans
Gergen's sounds like:
garczynski, georgians, gerashchenko, gershwin's, gorczynski, gorgons, gracing, graciousness, grasmick, grassings, grazing, greasing, gresham's, grisham's, groshong, grosshans, grossing, grossman's, grousing, grozny's, grussing, grzywinski, gurganious, gurganus