a crash course
A quick yet thorough tutorial on some topic or process. I got a crash course in answering the phones before the receptionist went on vacation.
crash course (in something)
a short and intense training course in something. I took a crash course in ballroom dancing so we wouldn't look stupid on the dance floor.
crash course
A short, intensive training course, as in Daisy planned to take a crash course in cooking before she got married. [Colloquial; mid-1900s]