The key to Sleeper Agent’s steady ascent, recently punctuated by their rollicking shows at SXSW, is disarmingly simple: the band members know how to laugh at themselves, and their songs are joyously melodic. (Possible motto, according to Smith: “Live faster, don’t die” —admittedly a work in progress.) You can hear this in particular on tracks such as the blogger-touted “Get It Daddy,” a dizzying school’s-out anthem about growing up, “Love Blood,” a jerky WTF about commitment, and “Get Burned,” the giddiest love-sucks tale you’ve ever heard that sounds like the Strokes doing the nasty with the Arcade Fire.