There are several synonyms for the phrase "forgot it" that can be used to express the same idea. Some of these synonyms are "neglected it," "overlooked it," "missed it," "disregarded it," and "let it slip." "Neglected it" implies that the action was intentionally not carried out, while "overlooked it" suggests that the person simply didn't notice it. "Missed it" implies that the event or thing was important, but the person was not able to meet it or attend. "Disregarded it" also implies intentional avoidance, and "let it slip" suggests that the person forgot something important accidentally. These synonyms can be used interchangeably to convey different nuances of the same idea.