Learn French: Il conduit comme un dingue.

Dingue is a very common informal word for crazy or nuts. Here it is used as a noun (un dingue) to mean a madman or a crazy person. It is colloquial (everyday spoken French) but not considered rude, so you will hear it all the time in casual conversations.

Is dingue originally an adjective or a noun?

It is originally an adjective, but here it acts as a noun! In French, you can often turn an adjective into a noun simply by putting an article like un, une, or les in front of it. So the adjective dingue (crazy) becomes un dingue (a crazy person).

Why use comme here instead of comment?

While both words can relate to how something is done, comme is used for comparisons to mean like or as. Comment is used as a question word meaning how. Since we are comparing his driving to a madman, we must use comme.

What is the infinitive of conduit, and why does it end in -t?

It comes from the irregular verb conduire (to drive). In the present tense, the third-person singular form is il conduit, ending in a -t. This is a great reminder because regular -re verbs typically end in a -d for the il/elle form (like il vend).