Sheyla Hershey has been reported to have the 38KKK bra. Another candidate is Chelsea Charms with the bra-size 61MMM. Maxi Mounds has the bra size of 36MMM.
That would be Sheyla Hershey of Brazil. She has a cup size of 38KKK. She holds the record as having the largest breast made of silicone. You can google her pictures.