intense
slang Serious or severe, perhaps to an overwhelming degree. That war movie was way too intense—I had to turn it off. Whoa, that accident sounds intense! Are you OK?
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]
intense
mod. serious; heavy. Oh, wow! Now that’s what I call intense!