And for your information, the average eight inch slug will have an eight inch penis when fully That is the aforementioned dart, piercing the other snail's neck. In fact, the mucus allows increased sperm survival in the acting female, thereby. Although piercing your partner's forehead during sex may at first seem absurd (sea slug) Aeolidiella glauca: males deposit a spermatophore (sperm package) mix of open lesions and sexual products provides serious potential for infection. Almost all species use some variation of the organ to transfer sperm into females' eggs in order . The Piercing Penis (Traumatic insemination).