What is the meaning of Dipstick?

A stick or rod used to measure the depth of a liquid. Often used to check the level at which a liquid in an opaque or inaccessible tank or reservoir stands; gauge.

The penis.

A useless person of inferior intellect; a dipshit.

To check (a person) for their understanding of something, as of a lesson, or attitude toward something.

To measure the level of a fluid using a dipstick.

Source: wiktionary.org