Impulse (1984)

Jennifer (Meg Tilly) is talking to her mother (Lorinne Vozoff) on the phone when her mom inexplicable shoots herself in the head. Jennifer and her boyfriend Stuart (Tim Matheson) rush to Jennifer’s small hometown to care for her injured mother and discover that she’s not the only one behaving oddly. Everybody there seems to be acting impulsively aggressive and Stuart thinks the cause may be chemical, though signs also point to a connection between the weird behavior and a recent earthquake. At one point, black and white pics of Jennifer stripping down on the dock of a lake are discovered, but those naked breasts belong to a body double and not Meg, though they’ll still have you acting out an impulse or two of your own!