"Whippin' Post", a classic. Listen to Zappa's version on "Does Humour Belong in Music" and try to cover that if you can. Dweezil and Frank going at with awesome guitar solos.
A few Tragically Hip tunes would be nice, "New Orleans is Sinkin'" is a dance tune that rocks, and for pure lyrical content "Nautical Disaster" is one of the better songs written in the last dozen years. I'd strongly suggest you pick up their live CD to start, "Live Between Us", if you can't find it easily in a local store you can order off their website www.thehip.com
It would be cool to cover the Hip cuz they aren't that well known in the U.S. but would be an audience pleaser for sure.
Oh, and depending on the "mood" of the crowd (and the aroma in the venue) you may want to slip in Pink Floyd's "Comfortably Numb"