Yup rhymes with:
bupp, chupp, closeup, cup, cupp, grupp, hupp, knupp, krupp, lay-up, pup, rupp, ruppe, schlup, schrupp, schupp, shupp, strupp, stupp, sup, trupp, up, upp
Yup sounds like:
yabba, yaffe, yap, yapp, yep, yip, yippee, yoffie, yopp, you've, yuba, yuppie, yuppify