In the heart of Soho, sandwiched between high-fashion flagships and design stores, is Seth Rogen’s first Houseplant pop-up, a “Gloopy” universe fit for Fegan Floop and the Thumb-Thumbs from “Spy Kids.” Complete with a rock-climbing wall, a cocktail—slash—ice cream bar and baby blue blob tables, it’s just as odd and as loud as the 43-year-old imagined it would...