Risks about contracting any sexual diseases, or about the other parties sexual behavior seems to be of little concern to you at the moment, because of your inward animalist drive to have sex right here and now. Nothing else matters your thought processes vanishes about the dangers of having sex with someone you do not know. Regardless of how this sexual interaction was consummated protected or unprotected sex and not knowing anything about this sex partner is it worth putting your life on the line for that second or for that moment.

With the many sexual diseases such as; gonorrhea, syphilis, Chlamydia, herpes, HIV (human immunodeficiency virus), AIDS (acquired immune deficiency syndrome) and many other sexual diseases in the public today and some of the sexual diseases are life threatening, would give you some pause about taking your chances to fulfill your sexual desire for the moment. When two individuals want to engage in risky sexual behavior with each other how much information does someone need to provide to the other person about their sexual disease processes or history. Before engaging in sex are you required to let the other person know that you have a sexual disease? Is having sex with someone a contract for both parties? What about your right to privacy regarding your medical history. Is only HIV (human immunodeficiency virus) the only disease that you must inform the other person, before you engage in sex? Before engaging in sex are you required to inform the other person that you have a sexual disease?

California Health and Safety Code Section - 120290.
"Except as provided in Section 120291 or in the case of the removal of an afflicted person in a manner the least dangerous to the public health, any person afflicted with any contagious, infectious, or communicable disease who willfully exposes himself or herself to another person, and any person who willfully exposes another person afflicted with the disease to someone else, is guilty of a misdemeanor."

Is having sex with someone a contract or agreement?
It is a verbal or implied contract, because both parties would have to agree and gave consent to have sex. Both parties share the same opinion that sex was the intended purpose.

Is having sex with someone a contract or agreement?
Verbal Contract:
Both parties have stated their intended purpose was to have sex and gave consent by engaging into sexual contact or conduct.

Implied Contract:
Both parties gave implied consent with their touching, feeling on each others' body parts, kissing the lips, and other body parts. Words were not necessarily spoken, but the act being performed.

California Penal Code 243.4 PC
The legislators created a law about sex and sexual touching. The law says that any sexual touching (buttock, or breast, or penis) without your agreement or consent is unlawful.
" (e) (1) Any person who touches an intimate part of another person, if the touching is against the will of the person touched, and is for the specific purpose of sexual arousal, sexual gratification, or sexual abuse, is guilty of misdemeanor sexual battery, punishable by a fine not exceeding two thousand dollars ($2,000), or by imprisonment in a county jail not exceeding six months, or by both that fine and imprisonment. However, if the defendant was an employer and the victim was an employee of the defendant, the misdemeanor sexual battery shall be punishable by a fine not exceeding three thousand dollars ($3,000), by imprisonment in a county jail not exceeding six months, or by both that fine and imprisonment. Notwithstanding any other provision of law, any amount of a fine above two thousand dollars ($2,000) which is collected from a defendant for a violation of this subdivision shall be transmitted to the State Treasury and, upon appropriation by the Legislature, distributed to the Department of Fair Employment and Housing for the purpose of enforcement of the California Fair Employment and Housing Act (Part 2.8 (commencing with Section 12900) of Division 3 of Title 2 of the Government Code), including, but not limited to, laws that proscribe sexual harassment in places of employment. However, in no event shall an amount over two thousand dollars ($2,000) be transmitted to the State Treasury until all fines, including any restitution fines that may have been imposed upon the defendant, have been paid in full.
(2) As used in this subdivision, "touches" means physical contact with another person, whether accomplished directly, through the clothing of the person committing the offense, or through the clothing of the victim. (f) As used in subdivisions (a), (b), (c), and (d), "touches" means physical contact with the skin of another person whether accomplished directly or through the clothing of the person committing the offense. (g) As used in this section, the following terms have the following meanings: (1) "Intimate part" means the sexual organ, anus, groin, or buttocks of any person, and the breast of a female. (2) "Sexual battery" does not include the crimes defined in Section 261 or 289."

As you can see and read any unlawful touching against another person's consent will get you into a lot of trouble, so do not do this. Always get consent from that person, before committing a sexual act.

What about your right to privacy regarding your medical history?
You have a right to privacy under normal circumstances regarding your rights to privacy of your medical history. But when it comes to your rights to privacy regarding your medical condition when you were informed or told by an doctor or physician that you have gonorrhea, or syphilis, or Chlamydia, or herpes, or HIV (human immunodeficiency virus ), or AIDS (acquired immune deficiency syndrome) and or many others sexual diseases, you have an obligation to inform your possible sexual partners of your condition.

California Health and Safety Code section 120290;
Except provided in Section 120291 or in the case of the removal of an afflicted person in a manner the least dangerous to the public health, any person afflicted with any contagious, infectious, or communicable disease who willfully exposes himself or herself to another person, and any person who willfully exposes another person afflicted with the disease to someone else, is guilty of a misdemeanor.

Is only HIV (human immunodeficiency virus) the only disease that you must inform the other person, before you engage in sex?
No you must report any sexually transmitted disease that you have acquired to a potential partner(s).

California Health and Safety Code section 120290;
Except provided in Section 120291 or in the case of the removal of an afflicted person in a manner the least dangerous to the public health, any person afflicted with any contagious, infectious, or communicable disease who willfully exposes himself or herself to another person, and any person who willfully exposes another person afflicted with the disease to someone else, is guilty of a misdemeanor.