Q: Could this person still be prosecuted?

A: The person who "falsely" admitted to "ejaculating" into someone coffee has put themselves in serious jeopardy of a sexual harassment civil claim. Such practical "jokes" can easily get the jokester fired and/or sued. Criminal prosecution is unlikely due to the higher standard of proof, but not impossible.

A: Telling the lie is intentional infliction of emotional distress for which your "someone" could be sued. Committing the act is a crime, and is intentional infliction of emotion distress, battery, and a variety of other potential civil wrongs.

A: Under California law, the scenario you described could potentially involve criminal charges related to battery or poisoning, depending on the specific circumstances and evidence. Battery, in a legal context, typically refers to intentional and unlawful physical contact with another person. If the act of contaminating the coffee was intentional, it could be considered as a form of battery.

However, for prosecution, there needs to be sufficient evidence to prove the crime beyond a reasonable doubt. If there's no physical evidence or witnesses, and the only information is the admission from the person involved, it becomes challenging to meet this standard. The credibility of the admission, the context in which it was made, and any corroborating evidence would be crucial.

If the person was lying about the act, it could complicate the situation. A false confession or admission can have various motivations and implications. It might not lead to prosecution for the original act (since it didn't happen), but it could have other legal consequences, like for filing a false report or causing emotional distress.

In any case, it's advisable to consult with a legal professional for guidance. Each situation is unique and requires careful consideration of the facts and applicable laws.