The word sis has many meanings but without context it's unlikely that we can help you.
Even though I have a hunch that you are quite young and infatuated with a Turk, I wouldn't suggest that what are looking for is the naughty meaning described here after:
Sis - fog, mist, haze, mistiness, haziness
spit, skewer, knitting needle, needle, swelling, swell, tumefaction, rising, bulge, wart, broach, concretion, turgescence
blown up, swelling, protuberant, swell, turgid
swell, swell out, swell up, become tumid, be puffed up, balloon, belly, bloat, bulge, bulk, distend, expand, fill, tumefy