kockati se

1. (kockati se) to gamble
   Njegov otac se kockao i izgubio sve. — His father gambled and lost everything.
   On se svake večeri kocka u kladionici. — He gambles at the betting shop every evening.
2. (kockati se + instr.) to gamble with; to risk
   Nemoj da se kockaš sa zdravljem. — Don't gamble with your health.

It is almost always used with se: kockati se.