From Warhammer 40k - Lexicanum
Mekboy Junkas are a type of vehicle used by Ork Mekboyz.
Often these vehicles are a way for younger Mekboyz to showcase their skill and talent in building vehicles and weaponry, hopefully impressing Warbosses and Nobz. Often derisively nicknamed 'junkas' by their peers, Junkas are sometimes scratch built or looted, but usually are a ramshackle cross of both. Like many Ork vehicles, each Junka is unique, incorporating the Mekboy's own special 'innovashuns'.
- 1: Imperial Armour - Apocalypse II pg.45