'banter train'

A group of 2 or more people (often, but not necessarily, LADS) embarking on a common journey to no place in particular, united by the sole aim of having a laugh.

Lad 1: Man, today is a slow news day.
Lad 2: Tell me about it...what times does the 'banter train' leave?

*Enter Lad 3*

Lad 3: All aboard! First stop 'Japes City'!