Not every foreigner knows this country has mandatory national services.
Not every single young Thai men between 17-27 joins military without a choice.
But roughly 80000 men are required to go the armed forces(either army, navy, air force).
Their conscription is based upon lottery; pick a ball in the Blackbox.
If you got black one. you can walk free; no needs to become a soldier.
If you got red one, bad luck...