The phrase "forbidden indulgence" implies that one is partaking in something that is not allowed or acceptable, but sometimes we simply can't resist the things that give us pleasure. There are many synonyms one could use to describe this feeling, such as "guilty pleasure," "taboo desire," or "secret delight." Some people may refer to it as a "naughty indulgence" or a "forbidden pleasure." Others may use words like "illicit enjoyment," "clandestine gratification," or "covert delight." Regardless of the words used, the feeling of indulging in something forbidden can be exciting and exhilarating. However, it's always important to consider the consequences of such indulgences and make sure they don't negatively impact ourselves or others.