While much attention has been directed at formal or academic writing in teaching and researching second language (L2) writing, informal writing still holds a marginal position in the current writing research, suggesting a neglect of its value as teachable in schools and meaningful for personal development. Adopting a phenomenological approach, the present study investigates L2 university student writers’ perceptions of and experience with informal writing both in and out of the classroom context. Drawing upon semi-structured individual interviews and written artifacts, this study revealed five themes pertaining to student writers’ experiences of informal L2 writing and demonstrated its learning potential as playground, situated interaction, and learning strategy. This study has implications for L2 writing scholarship with its situated and nuanced understanding of L2 student writers’ experiences of and engagement with informal writing. It also discusses the imperative for a refined understanding of L2 informal writing instruction and curriculum design