What's a sex positive culture? regardless if you want casual romantic or sexual relationship do it with someone out of the office. There are enough people in the world that you don't know anything about you can easily have a casual relationship with, there are apps for that, apparently.

A date assumes you have a more serious relationship in mind. No body cares if you marry a co-worker, it's causal relationships that could cause trouble. Besides, asking someone on a date is never ambiguous, and it can't be taken badly or out of context.