"Bloody oath" is an Australian slang phrase that means "absolutely true". However, there are many synonyms that can be used instead of this phrase. Some popular alternatives include "you betcha", "heck yeah", "absolutely", "for sure", "without a doubt" and "certainly". Other variations of the phrase may include "100%", "no doubt about it", "you can count on it", "definitely", "positively" and "indeed". These synonyms can be used interchangeably to convey the same intensity and sureness as the original phrase.