First, we didn't know a skin line needed a launch "summer trip;" second, we didn't know Kylie had her own private jet; third, we didn't know there was such a lovefest going on between Kylie and Sofia Richie!

Sofia was one of the VERY lucky FOK (Friends of Kylie) who was invited to go along on the Kylie Skin summer trip in a tricked-out, customized private jet in a matched pink-and-white tie-dye sweatsuit to a private villa on the tropical island in the Caribbean being waited on hand and foot by staff while she joins other ladies and Kylie's daughter Stormi living the high life in Turks and Caicos. Must be nice!

Sofia was posting TOPLESS pix of herself in a hot pink bikini, on the beautiful sand beach and Kylie commented, "perfection." So of course Sofia posted another one! And Kylie's been posting up a storm, to ... check out all her #twinning pix with BFF Stassi Karanikolaou! In fact, the two look SO much alike, commenters have made a point of pointing out how much their butts are EXACTLY the same ... to the point of them having the same doctor doing the exact same procedures, right? Kylie posted a pic of the two walking up a staircase side-by-side and one troll even said the two have more plastic in their derieres than there is in the ocean! So she removed the video (which we've got, coming soon) and replaced it with this pic (right) below ... so what do YOU think about these ladies' matching butts?!