横よこパイMeanings1nounside boobslangSlang term for the side of a woman's breast visible through clothing, especially from a side angle. Related to 横乳.See also: 横乳 · オッパイ彼かの女じょの横よこパイがチラッと見みえてドキッとした。I caught a glimpse of her side boob and my heart skipped a beat.