Some countries won’t approve your visa application if you don’t already have your flight home booked in advance. That makes it difficult for travelers without a fixed schedule or people who don’t know exactly how long they want to stay in a particular country.
Previously, if you needed a return ticket, you had to book a fully refundable flight (very expensive) and then cancel the flight as soon as you clear immigration in your target country.
I recently learned of another option.
BestOnwardTicket is a service that books a legitimate and valid airline ticket for onward travel to the country you desire in your name. You choose the ticket departure date.
The ticket they send will be valid for 48 hours. They will then do the work of cancelling the ticket. They charge $12 for this service.
I have no personal experience with this company, but I would use them in a heartbeat if I needed some real (fake) onward tickets to show an immigration official in another country.