A Halloween joke poster with the headline "Boo-ology!" answering a ghost riddle, in a playful, cute cartoon style. Rounded cream lettering with orange outlines and a 3D shadow sits stacked above a smiling ghost with an orange backpack, holding a purple book in a green classroom with a pumpkin and bats. Swap in your own riddle and punchline to make a joke card or classroom sign.

Create a finished square Halloween joke card for school, designed to remain readable as a small printed card or phone image. Use a bright, friendly children’s picture-book illustration style with crisp shapes, soft dimensional shading, and a warm classroom scene. Keep all artwork and text inside a generous 8% safe margin. Render only these two lines, spelled and punctuated exactly, with no other lettering anywhere: setup first, “What is a ghost's favorite subject?”; directly beneath it, the punchline “Boo-ology!” Make the setup a clear, single-line tier and the punchline the largest, boldest type on the card. Draw the letterforms as custom chunky, rounded display lettering with wide counters, open apertures, sturdy strokes, and even spacing; use bright ivory fills, saturated orange and teal outlines, and a subtle offset shadow. Keep every letter crisp and unobscured. Place the two text lines across the upper half, centered and separated by clear breathing room. In the lower half, show one smiling, sheet-shaped ghost wearing a small orange backpack, standing beside a classroom desk with a few colorful books and a simple chalkboard. The ghost gestures toward a floating book with tiny friendly bubbles shaped like little ghosts; no lettering or symbols on the chalkboard, book covers, or props. Keep the illustration clearly separate from the joke text. Use pumpkin orange, teal, violet, ivory, and a pale mint classroom background; add a few small star and bat silhouettes as sparse decoration. Soft even lighting, clean edges, no gore, no frightening details, no extra jokes, no logos, no border text, no watermark.