plop down

Verb

plop down (third-person singular simple present plops down, present participle plopping down, simple past and past participle plopped down)

1. (ambitransitive, informal) To sit or lie down heavily and inelegantly.
   • They plopped themselves down on the bed.
   • In surface America, it makes much more sense to slap a technical fix (mandatory [HIV] testing) on the "problem" and then not think about it anymore. That way we'll identify the pervert "carriers," put them away somewhere and plop down back in front of the tube with our minds untroubled.1988 August 20, Rex Wockner, “Nobody Can Do It Like The USA”, in Gay Community News, volume 16, number 6, page 5
2. (informal, transitive) To put down (something) in a heavy way.
   • He plopped his wallet down.
3. (US, informal, transitive) To pay.
   • I can't just plop down $50 for any old pair of jeans.