Prepositions in natural languages often appear to be governed by arbitrary conventionalized idiomatic uses (e.g., I was born in May, I will see you on Sunday). We present empirical evidence that such prepositional uses are not entirely arbitrary, as they activate image-schematic perceptual simulations during language processing. In Experiment 1, native speakers of English were prompted to think about either the date or the month of their birthday, and then select one of four calendar diagrams, two foils, one flat calendar and one box-like calendar diagram designed to invoke perceptual simulations of support and containment respectively. There was a significant relationship between the question prompt (implicitly eliciting in or on) and the type of calendar chosen (containment or support). Thus, spatial schemas can be spontaneously activated when thinking about time even for non-literal, idiomatic uses. Prepositional uses are notoriously difficult for English L2 learners. We surmised that improper prepositional uses may be linked to improper underlying perceptual simulations. This was confirmed in Experiment 2 where Japanese-speaking students of English were presented the same task as Experiment 1. Here, results indicate no relation between the date or month question and calendar choice. The experiments offer both theoretical and practical insights into how prepositions are processed by individuals with varying levels of language knowledge.