As others have pointed out, you don't need (or want) a corkscrew for champagne. Doesn't matter, real men don't drink pink champagne... if, indeed, there really is such a thing.

For those who take their wine seriously, there are an assortment of traditional emergency techniques for getting into a bottle of "real" wine. One romantic one involves using the back of a sabre... probably harder to find than a corkscrew, these days, and it purportedly takes practice. Another involves a fire and a wet feather. You can, of course, always push the cork in, but that's at least inelegant.

For whatever it's worth, I always take TWO corkscrews when travelling. One has to prioritize one's survival gear, after all...