From what I understand and have read there are two ways to determine the sex of a pacman. The first is to look closely at its nose. If the nose is kinda blunt or smashed then its a male, if the nose is more elongated and pointy then its a female. Now this method is not a 100% certain method to sex these frogs. The other method and this method is for sure is to determine the sex by its noise. A male will puff up its throat and collapse it to create a croak sound which is the frogs mating call. A female will "growl" and then "bark" while lifting its rear in the air as a defense mechanism. I hope these tips have helped you, and let me know if my information is inaccurate, I did get it from the internet so you never know.