You can ask her if it's going to be a quickie. If she answers in an angry tone because of the sexual intent, then tell her you just wanted to know if it was a quick bite to eat and brief discussion. If she hints around that maybe doing the naughty thing is a possibility, then you know things might be better (or she wants something). So, there's the perfect temp-check.
Disclaimer: I'm the absolute worst DBer in the universe, but right now I could use a quickie.
