plunk down v.,
informal 1. To drop down; fall.
After walking a mile we plunked down on a bench to rest. 2. To drop something noisily or firmly.
He plunked the heavy suitcase down at the station. 3. To pay out, primarily an excessive amount
I had to plunk down $55 for a concert ticket. [TahlilGaran] English Idioms Dictionary ▲