In various world languages we have words where mouth acts as an approximate measuring unit. In Judaism, e.g. on the day of Shabbat (i.e. Saturday), one is not supposed to carry more than a cow’s mouthful of straw, a camel’s mouthful of bean stalks, a lamb’s mouthful of clover, a goat’s mouthful of grasses etc (refer Mishnah Shabbat 7.4). One interesting point is how we use different measures for solids and liquid in terms of mouth units. E.g. in Hindi / Urdu, following are some words related to human mouth as units of quantity:
Linguistica Indica 