You have every right to refuse a sexual gift. Sexual gift-giving is a prohibited form of sexual harassment. Therefore, you cannot get fired from work for refusing a sexual gift.
You cannot face any forms of retaliation if you refuse a sexual gift or report the sexual gift to your boss or HR. Retaliation, such as wrongful termination, demotions, denied raises, altered shifts, negative employee reviews, and more, is prohibited under state and federal sexual harassment laws.