Jelqing is a method intended to enlarge the penis by exercising the smooth muscle and other tissues in the penis, with the goal of permanently increasing the maximum erect size of the penis. This technique, also called "milking", involves wrapping the thumb and index finger around the penis while semi-erect and repeatedly drawing them away from one's body to force blood into the glans, thus encouraging more vascularity in the corpus cavernosa and associated tissues. There is no scientific evidence that this technique actually works.

Risks that exist from this exercise are: burst blood vessels, sometimes causing bleeding from the urethra (which can lead to infection and other complications if not taken care of), and temporary or even permanent erectile dysfunction.

There are many products (tools, instructions, etc.) that one can buy; however, much of what they offer (instructions) is available on forums and free websites.

Jelqing is typically preceded by a warm-up with a hot compress on the genitals, and concluded the same way. The reasoning behind the 'warm-up' mimics the normal operation of the biological processes of the penis during the four stages of arousal. The third stage is heat. At this stage the smooth muscles of the 'glans' can easily expand to their present (not future) greatest potential size.