If it's on a college campus, the speedo run around the atheltic field would be just great.
I just swim in speedos, but for running I just wear pre 90s style gym shorts. However here in San Francisco, I notice a lot of guys (about 50%) out running on the water front in marathon style short shorts.
BTW, I'm think about organizing a Speedofest by placing an ad on Craigslist.Com and telling guys that on a certain date (usually a Saturday) they should go swimming in speedos and running in marathon shorts.
CD