先森玩心么
[xiān sēn wán xīn me]
'先森' is a phonetic play on words which resembles both the term for mister/sir (先生) and forest/cellulose (木质纤维), often used in a casual or playful context; '玩心么' could suggest mischievousness or the heart of playing/trifling with someone or just having fun and whimsical, not very seriously engaging.