Please tell us your plans, eg are you coming with a visa or getting stamped in for 60 day visa exemption, if the latter and you are just on hols and have a return ticket dated no longer than the 60 then this is your onward/return out of Thailand. If you intend to extend your 60 days then the airline will need to see a ticket that you have a ticket out no later than the 60, you can by cheap onward tickets and not use them.