A frenulum piercing, known as a frenum, is a piercing of the frenulum preputii penis, which is an elastic band of tissue under the glans of the penis. While many people find it aesthetically pleasing, the most common reason given for this piercing is the enhanced sexual pleasure that is often reported by males with the piercing and especially their sexual partners.

Frenums are usually done perpendicular to the shaft, but piercings running parallel to the shaft are possible. Variations on the frenum include the frenum ladder, which is a series of frenums in a row, or the frenum loop, where a single ring is attached by a frenum piercing and encircles the shaft.

The frenum is usually considered an "easy" male genital piercing. It is usually one of the least painful male genital piercings, and has relatively few reported healing complications.