Soupy things have the texture and thickness of soup. If the sidewalk is covered in soupy, half-frozen slush, you'll want to wear your boots.
Anything that reminds you of soup, especially in consistency, is soupy. Your favorite dish at an Indian restaurant might be a spicy, soupy mix of spinach and cheese, although you may prefer the cardamom ice cream to the soupy rice pudding for dessert. You can also use soupy for something that's overly sentimental or sappy: "She sent me this soupy Valentine's Day card, but I was hoping for chocolates."