"Smackeroo" is a playful word used to describe something that is particularly impressive or noteworthy. It is often used to express admiration or appreciation for a job well done. There are a number of synonyms that can be used in place of "smackeroo" depending on the context of the situation and the specific connotations that are desired. Some possible options include "wow", "awesome", "amazing", "fantastic", "incredible", "unbelievable", "magnificent", "stunning", and "spectacular". Each of these terms conveys a slightly different sense of amazement or appreciation, so it's important to choose the right one for the situation at hand.