My first question is - How long can ejaculated semen survive into a fabric (for example, boxers) ?
The second question needs a bit of explanation of the situation first - If a man, who wears boxers and training trousers, ejaculates inside of his boxers (wearing trousers too), after like 40 minutes beggins to hump with a woman, who only wears trousers, around her vaginal area, could the sperm somehow make its way in to the vagina, if the trousers are a little wet from the ejaculation?