Fear of impregnating someone
One of the common themes of OCD is fear of harm or fear of causing harm to oneself or others. This is a fear of accidentally impregnating a woman even if no intercourse occurred.
Common compulsions include excessive hand and whole body washing, especially after masturbating, using several forms of birth control simultaneously, avoiding public showers, gyms, swimming pools, and saunas, asking for reassurance, etc.