“Spaz” isn’t just the name of a N.E.R.D. single — it’s what Pharrell, Chad Hugo, andShae do all over the group’s third album. Without warning, hard techno explodes into jazzy bridges; stiff quarter-note rhythms dissolve into Edge-y riffage; and a lyrical motley crew of Peeping Toms, playas, and suspiciously peppy club girls pop up to say their piece. Oh, there are also six amazing minutes of Hendrix-like splendor called “Sooner or Later.” N.E.R.D. may not settle for one cowbell when 100 will do, but they kick like a bucket of Red Bull — and go better with vodka, too.