Grock - thats a proper scouse saying, as in "yer fookin big grock"
Haven't heard it for years, means big hard looking person but not particularly intelligent, think 'Shake Hands' off Boys From The Black Stuff.
Another one which I genuinely don't know is scouse or not is 'yard dog'. Now I think it could mean one of two things if I mentioned it in a pub, the first is a particular type of footy player, think the entire Everton squad, think Harry Maguire....... the other meaning is a cross-bred dog that sits outside all day, or the types that used to live on the roof of pubs on estates in the 80s and 90s and would bark down at you if you walked past. There was a few on Canny Farm.