:g: they're wearing dark suits and it is a dark club. Plus, they're an acapella band. Allll about the stealth harmonising to make you go 'ooo, this is nice, holy fuck, where did *that* come from?'. I blame myself - I'm easy to pick out because I'm normally wearing bright red and/or white when venturing out - combine that with the blonde, loud and glued to dancefloor factors...