I’d like to draw your attention to this excellent article, written by a law professor, explaining consent with a series of scenarios that should be suitable for even dudebro-levels of reading comprehension. One thing becomes clear by the time you are finished reading it:
There’s really no excuse for being unclear on the concept of consent.
So please, send this one to those folks you encounter who, when faced with sexual situations, waffle about what consent is. Are you arguing with a person over whether drunk women can consent to sex? Have them read this article. Are you trying to get through to someone that prior consent to a sexual act or activity is not ongoing consent, and that consent may be revoked at any time? Send them this article. For any person who claims that consent is murky in any given sexual situation, have them read this article.
And then, if they still claim that consent is unclear, you can take that as their having given you consent to borrow their car whenever the fuck you please.
I’m pretty sure they’ll be crystal clear on the concept of consent the first time you take their keys.