plopping out welcome matts!The hashtag #UpsideDownPineapple has clocked up a whopping 138 million views on TikTok as Wednesday afternoon, with some clips claiming swingers even leave an actual pineapple upturned out front of their Airbnb accommodation to indicate that they enjoy partner swapping. “People’s sex drives tend to go off the charts during vacations,” John Kamau, CEO of the hook-up app Cruise Ship Mingle, told The Post, saying he’s shocked by the number of swinging couples signing up for his, uh, pineapple-friendly service.