Brum Brum Car
Similar to a Coal Car with the distinction that Brocks mum, fitted with a strap on, is the Coal Car and Brock is the engine.
Zac: You in for a man train tonight?
Brock: Only if Mum's the Brum Brum Car and I'm driving
Brock: Only if Mum's the Brum Brum Car and I'm driving