Even in the era of ridiculously low airfares, we can still be surprised at just how low flight prices are getting. And $15 tickets are never going to stop being surprising. Budget airline Frontier currently has pages of $15 flights to and from all over the United States, and you almost can't afford not to buy one.
These are part of Frontier's "Penny Plus" fares, where the airline sells flights for a penny, plus taxes, which comes out to one-way flights for $15. The days you can travel at these rock-bottom rates are fairly limited and on a location-by-location basis, so you'll probably only end up with a super-cheap fare one-way. This deal is only available by midnight on April 19, so you'll have to book soon.
Flights are featured from all over the country, with $15 fares heading out from cities like Atlanta, Austin, Birmingham, Charlotte, Chicago, Cincinnati, Denver, Milwaukee, Philadelphia, Seattle, and Washington, DC. And the places you can fly to are just as varied. You won't be getting to or from New York, Los Angeles, or San Francisco, but maybe take this chance to finally check out Colorado Springs. Or Las Vegas, if that's more your speed.
Note that Frontier is a low-cost carrier, which means you'll be charged for luggage beyond your personal item, plus there'll be a fee for seat assignments. But you're also traveling the country for less than the price dinner.
So, maybe book two seats immediately and figure out who's coming with you later.