Do I need proof of onward travel to enter Ukraine?

Of course. Coming to Ukraine without it can get you in problem. you need it for your visa application proof of round-trip.

What happens if go to the airport without this Proof of onward thing

Colombia require most of the countries in the world to show round-trip ticket to get visa. if you one of the countries who get visa by entry you also most likely will have to present proof of onward travel so be prepare for it.

How I get Proof of onward travel To Ukraine like a boss?

The simple way to get Proof of onward to Ukraine without paying is using Trixo you can generate dummy ticket in seconds for any country with any airline. 

People also search; Return ticket to enter  Ukraine , Proof of onward travel for Ukraine, travelling to Ukraine in a one-way ticket.