[[Measuring]] a [[penis]], a phallic object, or the depth of a possible penetration. Typically presented as either using a [[ruler]] or a [[body writing]] on the receiving end's stomach to gauge "pleasure" based on the reach.

Pixiv's tag-equivalent is "kafukubujougi", "lower-abdominal ruler".

h4. See also

* [[penis chart]]
* [[bust measuring]]
* [[penis envy]]
* [[penis awe]]
* [[penis on stomach]]
下腹部定規