čačkati

1. (teeth, nose) to pick
   Ne čačkaj nos, to je ružno! — Don't pick your nose, it's gross!
   Posle ručka je čačkao zube čačkalicom. — After lunch he picked his teeth with a toothpick.
2. colloq. to fiddle with; to poke around
   Nemoj da čačkaš po mom telefonu. — Don't poke around in my phone.
   Stalno čačka taj prekidač i pokvariće ga. — He keeps fiddling with that switch and he'll break it.
3. colloq. (the past, a topic) to dig into; to stir up
   Zašto stalno čačkaš po prošlosti? — Why do you keep digging into the past?
4. colloq. (of a person) to tease; to bother; to provoke
   Ne čačkaj me, već sam nervozan. — Don't wind me up, I'm already on edge.

In the sense "poke around" it is usually used with po + locative.