A few years back Wendy's had an offer where if you got a medium or large drink there was a coupon on it. 32 coupons got you a one-way flight in the continental US, 64 got you a round-trip flight. Being a poor college student at the time, a few friends and I went dumpster diving at all the local Wendy's and over a couple nights ended up getting about 4 round-trip tickets. The only drawback was having to throw out those clothes..