drobiti

1. (bread, stone) to crumble; to crush
   Deda uvek drobi hleb u supu. — Grandpa always crumbles bread into his soup.
   Mašina drobi kamen za izgradnju puta. — The machine crushes stone for road building.
2. colloq. (of talking) to talk rubbish; to spout nonsense
   Šta to drobiš, ništa te ne razumem? — What are you babbling on about? I can't understand you.
   Ona drobi već sat vremena o svom šefu. — She's been spouting nonsense about her boss for an hour.

In the sense "to crumble" it takes a direct object: drobiti hleb, drobiti kamen.