Blonds Have More Fun(1979)

Herb is a two-time con artist whom schemes with his partner Brains and his teenage assistant Wendy Wilson to create a new type of love potion. But when it sells big Herb does not expect the results to be this gratifying when all over San Francisco do people whom drink from it get the instable urge for sex, from a derelict in a local whorehouse, to lovers in quarrel, and the various customers.