In mobile crowdsourcing, labour can be opportunistically elicited by sending notifications to workers who complete tasks on-the-go. While much work has focused on optimizing the work quality and quantity in mobile crowdsourcing, surprisingly few studies have explored the type of tasks that might be suitable for different user contexts. This paper presents results from a proof-of-concept user study that aimed to uncover where, when and what type of tasks mobile workers are willing to complete. We find that different contexts do affect the type of work users are willing to complete. Finally, we lay out a complete design, key challenges and opportunities for a longer field trial that we hope to conduct in the near-future.