To throw or move (something) quickly, usually with an impact. He angrily whopped the book onto the table. Whop is a verb primarily used in informal English, often in a playful or light-hearted context. It means to strike or hit hard.

whop (third-person singular simple present whops, present participle whopping, simple past and past participle whopped) (transitive, informal) To throw or move (something) quickly, usually with an impact. He angrily whopped the book onto the table. 1848 October 28, “Collectanea.