What does this translate to? ㄨㄞ
It is Mandarin phonetic symbols commonly used in Taiwan.

See:


http://lib.ctcn.edu.tw/chtdict/zhuyin_2.aspx?ZhuYin=%E3%84%A8%E3%84%9E&amp;TopZhuYin=%E3%84%A8
https://en.wikipedia.org/wiki/Mandarin_Phonetic_Symbols_II#Finals


When printed on tee-shirt in this way, I think it means something naughty, happy and enjoyable.  See https://zh.wiktionary.org/zh-hant/%E7%88%BD%E6%AD%AA%E6%AD%AA