Leather jackets, Alex? What would your 18-year-old self think? The band were on the David Letterman Show and performed latest single ‘Don’t Sit Down Cause I’ve Moved Your Chair’. David Letterman is excited by the new album, Suck It And See, out on Friday in Ireland. Don’t they look like they’re having loads of fun? We All Want Someone has some recordings of Alex playing a few tracks from the new album with just an acoustic guitar and a pair of sunglasses. Indoors…