underboob this summer thanks to the revival of the “upside-down bikini” craze that’s got the internet howling for haltered hooters. Kylie Jenner and her K-clique kin seem to be responsible for resurrecting the sexy swimwear style that has her and sisters Kourtney Kardashian and Kendall Jenner baring more breasts. The topsy-turvy bikini top trend was first made popular by Italian influencer Valentina Fradegrada in 2018 — the same year it was declared the “worst thing on Instagram.” But The Post