Literal meaning is pole. In this context, figuratively to shove the pole up someone's ass. also used to connote that someone is nagging or irritating constantly.(Balli kar dena)
Champu : Hey Raaka...that junior is acting like a hero, maams...trying to chat up our batch chicks.
Raaka : Saale ke gaand me balli kar denge ( we'll shove a pole up his ass...)
Champu: Hey Raj, you owe me 10 bucks for yesterday's samosa..
Raj: Gaand me balli mat kar, de doonga..(don't nag me, I will give it back)
Added 2014-11-24 by K_TR