Delinquent School Girls (1975)

aka Delinquent Schoolgirls, aka Carnal Madness, aka Delinquent College Girls, aka The Delinquents, aka Love Maniacs, aka The Sizzlers, aka Scrubbers 2 

How bad is it? It's brainless and extremely sophomoric.
Should you see it? I loved it (though it's slow), but only recommend to sexploitation fans.

Those aren't the biggest stars of this film.

The plot has three escaped convicts terrorizing a girls' school. When anything plot-related happens, though, the film bogs down; that's not why anyone would watch this. The movie has every possible exploitative cliche imaginable and it's fun to see how they manage to work into the plot, say, a girl bouncing on a trampoline - twice. My favorite line runs something along the lines of, "We're not going to take it any more. Let's show them! Let's not wear our bras today!" This is the only film of Roberta Pedon, who was young, slender and pretty and had enormous breasts (that were actually appealing); that her accent is so thick one can barely understand her lines explains why Russ Meyers never used her in a film. The IMDB bio of Pedon appears to be at least 80% fabricated, but she disappeared in 1977 and generally is believed to have died soon after.

Update: I believe Pedon's still alive. Here's a photo of her in 1974 and one of someone I think is her more recently: