Wordnet 3.0
VERB (1)
1. 
 set (something or oneself) down with or as if with a noise; 
- Example: "He planked the money on the table"- Example: "He planked himself into the sofa"[syn: plank, flump, plonk, plop, plunk, plump down, plunk down, plump]
WordNet (r) 3.0 (2006):
plunk down
    v 1: set (something or oneself) down with or as if with a noise;
         "He planked the money on the table"; "He planked himself
         into the sofa" [syn: plank, flump, plonk, plop,
         plunk, plump down, plunk down, plump]