Two unreleased collaborations between will.i.am and Justin Timberlake leaked this week, one a sober reflection on social issues and the other a party song about finding some "high-class sexy ladies."

Timberlake sings the chorus on the mid-tempo 'Nature of the World,' which examines problems in the world, much like his collaboration with the Black Eyed Peas, 'Where is the Love?,' which earned a Grammy nomination for Record of the Year in 2004.

The Timberlake hook on 'Nature of the World' ended up on another song, Talib Kweli's 2007 track 'The Nature.'

The other leaked track, 'Going Crazy,' feels a lot like a typical BEP song, with lively percussion and a dance-pop vibe. JT sings about "lookin' for some city girls with big fat country butts," while will.i.am encourages them to "shake it like an earthquake."

It's unknown when the tracks were recorded, but Timberlake hasn't released an album since 2006, though he does plan to record new music again at some point. will's last solo record, 'Songs About Girls,' was released in 2007.

Listen to will.i.am & Justin Timberlake, 'Nature of the World'

Listen to will.i.am & Justin Timberlake, 'Going Crazy'