If you're ever in a situation where you need ear plugs (on a commuter airline, in a hotel bedroom that is noisy, at a rock concert) and you don't happen to have a pair in your purse or pocket, here's what a friend of mine did. Take a piece of tissue paper and tear off a 2" square (larger if you have big ears). Crumple it up and check that it will fit in the ears. Next dampen it and insert it into each ear. Voila, you have ear plugs. It may look silly, but it works.
If you can plan in advance, I'd suggest you look into buying an ear plug called EarPlanes especially if you fly often. They seem to eliminate ear discomfort and popping when the plane is taking off and descending .