* No penetration: Frottage, by definition, does not involve penetration. Sperm needs to reach the egg for fertilization to occur.
* Menstruation: During menstruation, the uterine lining is shedding. Even if sperm were somehow to get inside, the environment is generally unfavorable for implantation.
* Tampon: A tampon acts as a physical barrier, further reducing the already slim chance of sperm reaching the cervix.
In summary: While *theoretically* nothing is impossible, pregnancy from this scenario is highly, highly improbable. However, it's important to remember that STIs can still be transmitted through skin-to-skin contact, even without penetration.