Despite his tendencies toward eff-it-all wisecracks, non sequiturs, practical jokes, and general older-brother humor, the quick-tongued Pete Wentz can and does get serious about supporting important causes — he and Fall Out Boy actively support Invisible Children, and Pete has spoken openly about his experiences with depression for mtvU’s Half of Us mental health awareness campaign.

Last night, on the red carpet at the 2008 NME Awards in L.A., he took a decidedly punk rock approach to consciousness-raising, specifically about coltan, a mineral mined in the Congo — usually illegally and often at the expense of human lives — used in everyday electronics and appliances like laptops and cellphones.

While, to some, Pete’s DIY t-shirt might’ve looked like a last-minute party stunt, he’s actually been sending out a message about coltan for a while now.

See what he told us last month about the bloody resource in this exclusive interview. Plus, find out more about coltan here and here. (And, in case you were wondering, yes, Ashlee’s bling is blood-free.)