译愿您开开心心，
（愿您）笑口常开，
（愿您）周末愉快！
注smile本来就是可数名词，自然可以用作复数。《牛津高阶英汉双解词典》有例句曰：He had a big smile on his face. 还有一个习惯用语与smiles有关，即：be all smiles。该习语中，smile为名词，且必须加s，《牛津习语词典》释义为：be very happy and smiling, especially after feeling sad or worried about something. 在这里，smile用作复数，不妨译作：笑口常开。