It's the tattoos across those young faces that are so striking. Next to them, the accompanying rainbow locks, "iced out" teeth grills and audacious fashion choices fade in comparison. Imagine gazing across the breakfast bar at that: it's the stuff of a parent's nightmares.

The facial ink is just one hallmark of SoundCloud rap, a once underground scene with its roots in southern US trap music that in the last year has crossed over into the mainstream, and is fast becoming one of the most popular musical genres for teenagers and young adults.