I entered the country a few weeks ago, booked the ticket 1 day prior..If you are not a resident of Argentina, there is a high chance they'll ask for a return ticket. What I always do: I buy the cheapest ticket I can find the morning of my flight to Argentina, as it takes me 12 hours to get there, I cancel the ticket once I clear customs at the airport in Argentina. I think all airlines fully refound any tickets canceled less than 24 hours after booking.
no return ticket and nothing..
I guess it's a little bit who checks you