lupati

1. (na, u + acc.) to knock; to bang
   Neko lupa na vrata već pet minuta. — Someone has been banging on the door for five minutes.
   Komšije gore stalno nešto lupaju. — The upstairs neighbours are always banging something.
2. (+ instr.) to slam; to bang
   Nemoj da lupaš vratima kad izlaziš! — Don't slam the door when you leave!
3. colloq. to talk nonsense; to talk rubbish
   Šta lupaš, to uopšte nije istina! — What are you on about, that's not true at all!
   Ne slušaj ga, on samo lupa gluposti. — Don't listen to him, he's just talking rubbish.
4. (of the heart) to pound; to race
   Srce mi je lupalo pre ispita. — My heart was pounding before the exam.
5. colloq. (of a person) to hit; to beat
   Stariji brat ga je stalno lupao. — His older brother was always hitting him.
6. (+ acc.) to smash; to crack open
   Baka lupa orahe za kolač. — Grandma is cracking walnuts for the cake.
   Lupaj jaja u činiju, pa ih umuti. — Crack the eggs into a bowl and beat them.

To slam a door is «lupati vratima» (instrumental), while to bang on a door is «lupati na vrata».