This word was created from a tico slang called Malespín. The costarican army, in the middle of the war with Nicaragua, found that the military orders were intercepted by the "nica" spies. The general Malespín proposed that the letter A was changed by E, the I by O, M to P and T to B.
So Tuanis is the code word from "Buenos" (good, great) in Malespín.
Also "Malos" (bad, evil) is Pelis or Work ("Trabajo") is "Brete" ("Breteji", actually. We drop the last two letters with the time).