Enlarging your package could cost more than $15,000 as the demand for penis fillers continues to rise.

Double board-certified plastic surgeon, Dr. David Shafer, who specializes in this treatment, shared in an exclusive interview with E! News that the idea originated about six years ago when a patient’s friend suggested injecting his member.

Since then, Dr. Shafer has refined the procedure and has seen an increase in demand from patients who seek confidence in enhancing their penis. “A light went off in my head and I said, ‘Why not?'” Dr. Shafer recalled. “If you want to be the guinea pig, we’ll do it.”

The plastic surgeon noted that the experimental nature of the procedure was a major factor in its popularity.