The phrase "gosh-darns" is an expression of frustration or annoyance, but it may not be suitable in all situations. Therefore, it's essential to have some synonyms to replace it while preserves the intended meaning. Some of the choices available include "dang it," "blast it," "heck," "drat," "curse," "beat it," "rats," "shoot," and "sugar." Each of these words has its own nuances, so it's wise to choose one that best fits the situation. That way, you can express your frustration without offending anyone or coming off as unprofessional.