A lot carnival games are targeted at kids, with good reason. Adults bring their kids to carnivals so that they can hop on rides, play games and win prizes. Carnivals used to be full of adult attractions, though, and there are plenty of adult-oriented carnival games to get those moms and dads to come without the kids.
A lot of sports booths are geared toward children and have prizes that don't compel adults to play. Try active, sports-based games with sporting goods or posters for prizes. Set up a baseball or football throwing game with prizes for speed or accuracy. Basketball games with high goals and narrow rims challenge adults because they look easy. There are booth possibilities with nearly all kinds of sports, including bowling, darts, shooting, golf, soccer and hockey.
Dunk booths are popular at carnivals, but for adults there are some variations that make it more appealing. Instead of a laughing clown, get a police officer or a local official to sit in the booth so adults might have a reason to want to dunk him. You could get somebody to berate people and goad them into playing. For an R-rated dunk booth, you could have good-looking men or women wearing bathing suits or white t-shirts in the booth to tempt people into playing.
While you shouldn't have an actual casino game at a carnival for legal reasons, you can have similar games that offer prizes or tickets. Blackjack works well for a booth because the worker can have multiple players at once. Dice throwing games also work well, in which the player wins a prize for rolling a certain number or pair of numbers. These games are family-friendly, and can be enjoyed by adults and kids alike.
Destroy the Car
Adults like to let off steam. Put an old junk car and some sledge hammers in a roped-off area or booth. Men and women alike will pay money to get a few minutes alone with the hammers and the car. Once they start breaking glass and denting metal, they won't be able to stop. Of course, provide participants with safety glasses and gloves. Taking the windows and mirrors out is a good idea, especially for old cars that don't have shatter-resistant glass. After the carnival, you can sell the car for scrap metal. When hosting a destroy the car booth, include a disclaimer that you aren't responsible for injury and don't allow more than one person in at a time to prevent injury.
Carnivals are known for cotton candy, turkey legs and rides, but some people go to drink. Have drinking booths where people compete to drink faster than each other or a set amount of time for prizes. Challenge them to drink three pints of beer in less than 30 seconds, offering the beer for free. If they don't do it, they have to pay. This would work with soda or water as well, but beer might lure more people. Don't use hard liquor since people might get quite sick and remind your players to drink responsibly.