"So, do you fuck on the first [or second, ...] date?"

I thought this up as a joke to myself, but decided it could actually work. Ask playfully but with a hint of seriousness. It's now on the table but in a potentially joking manner. Could be used on a boring date you're attracted to, if you're impatient and don't think an additional date is worth it if she won't put out, girl you just met, etc. The more I think on it the more it seems like it could be a situationally great line, but I don't want it to blow up in my face.