Avon and Somerset Police are aiming to raise awareness about the risk of date rape, as one of the busiest party weekends of the year approaches.
The force said such attacks were eight times more likely to be by an "acquaintance" than by a stranger.
Officers said they wanted to highlight the message ahead of Christmas and the New Year since acquaintance rape was closely linked with the social scene.
Alcohol was said to feature in 54% of all reported acquaintance rape cases.
Supt Steve Jeffries said: "Predominantly, acquaintance rape refers to those cases where two people who know each other previously, or get to know each other that evening, meet up in a bar or club and head back to one of their homes at the end of the night and things go too far.
"The most important thing to stress, however, is that if you have invited someone back to your home and have been drinking with them earlier in the evening, these factors are not an indication of consent and you are not to blame. If consent was not given, it is rape."
He added that victims were often ashamed to come forward, but he said police would take all reports "extremely seriously".