"Nannuk trab" means your grandpa is dust,basically he died and now he is dead and dirty.
It is commonly known in Maltese language ..
Jamie:"Aw Luca"
Luca:"Int min izzob int foxx missierek"
Jamie:"uwejja ghala qed tghajjarni"
Luca:"Nannuk Trab"
Or
Sister:"where is grandpa?"
Brother:"Since last week,Nannuk Trab"
Basically this is a phrase used in the maltese language, Nannuk Konkos. This phrase means that your nannu is buried under the concrete which means he is dead.
- Aw bro orrajt jew?
Le man Nannuk konkos