Is having sex the day after oral surgery safe?

It depends: On what exactly you had done. Oral surgery procedures cover a wide range from a simple tooth extraction to major facial reconstructive surgery. If you had a simple tooth extraction or a dental implant placed, then there shouldn't be an issue. If it was more extensive, then it could be. If you are unsure, contact your surgeon.

Sex and surgery: Only if you use a condom. Lol. Seriously it probably won't cause any issues unless you get really physical during intercourse and really raise your blood pressure, this could end up loosening the blood clot and causing dry socket. It could also depend on the type of surgery you have. If you are having orthognathic surgery where they are sectioning your jaw then I would say "don''t do it".