Helmberg

Helmberg is a word for describing someone who is completely disconnected from the rest of the world and has no idea what's going on, Helm being part of the word Helmet and Berg for ice berg, the relation is they are so disconnected they could get hit by a boat like the titanic and have no clue what is going on

"Oi Jon, did you hear back from Sam?"
"Nah, that geezer hasn't got a clue bruv, absolute Helmberg"