1. int. watch out (presumably for some inadvertent calamity)
2. int. exc. watch (it or yourself)
3. int. exc. to indicate something unique or beautiful that needs attention drawn to it.
1. "Wachale! There's a big pile of dog excrament on the flooor!"
2. "Esmerelda told Vicente 'Wachale!' when Vicente inadvertendly bumped her during P.E. 3a. "Wachale! Look at that man's head explode in DEATH MARCH 7" 3b "Edgar shouted 'Wachale!' to his friends when Mariana walked by."