大人的快乐怎么说英语

The phrase "adult joy" could refer to the happiness and fulfillment that adults experience in their daily lives. Some ways to express this in English might be:
"The joys of adulthood"
"The pleasures of being an adult"
"The happiness of grown-up life"
Alternatively, you might be asking about ways that adults can find enjoyment and relaxation. In that case, some options could include:
"Ways to have fun as an adult"
"Activities for adult leisure and enjoyment"
"Finding joy in the everyday as an adult"
I hope this helps! Let me know if you have any other questions.