A filmmaker once produced a B-grade movie. The costuming and dialogue were characteristic of the mid-20th century, but the giveaway today was that the production was in black and white.
In any event, not only was the acting quality quite B-grade, but the plot was genuine B-grade - outrageously immoral for its time and noticeably lacking in any serious intent.
According to the story line, such as it was, a group of tourists took a train into one of the more wooded areas of what must have been Switzerland, or perhaps northern Italy. Through a series of mishaps they became separated, and each of the half-dozen couples ended up in one or another fairly sleazy hostelry - not knowing that a rather unsavory character was roaming the neighbourhood.
The first couple had barely made it into their bedroom, dressed (or, rather, undressed) for the night, and hopped into the sack, when the killer broke through the window and ended both their vacation and their lives.
As the second couple, in their respective seedy room in their own seedy hotel, had just jumped into the sack, the through-the-window motif was repeated, with the predictable result.
This went on and on for an hour and a half.
Most viewers never knew if the killer was caught or met his own end - by the end of the film they'd either left the theater or fallen asleep waiting for a truly pornographic scene.
Needless to say, this immemorable contribution to cinema history was panned by the critics of the time as a mere vehicle for sacks in vile inns.