The Little Shop of Horrors is well known, possibly Roger Corman's most famous movie. That's for a few reasons, the debut of Jack Nicholson as a demented dentistry patient and the fact this movie seems to be on just about every collection of horror films I own. Only Last Man on Earth beats it out for sheer volume. Also they made a musical and then a movie and such and while I've never seen those all the way through, I already know I prefer the original.
The story you all know, a nebbish working in a flower shop crosses two plants, a Venus Flytrap and something else, and creates a deadly man and woman eating bit of flora. It also talks and demands the human blood on which it thrives and the nebbish for some reason caves in and kills for it. The shop owner suspects, but his store is being saved financially because of the curiosity about the plant and so he turns a blind eye. Eventually of course it all goes sideways.
The Little Shop of Horrors is more of a pure comedy than its immediate predecessor from Roger Corman's Filmgroup A Bucket of Blood. The latter was rife with satire and while the movie has such a lark with the broad characters there's little tension. The Little Shop of Horrors is available on every other collection of horror movies ever done since the beginning of time so it's easy to find. Just look, you probably own it.