Something about the hook-laden songs of the Cars really begs for lewd lyrics. This song is probably reviled by many because it's a slow, depressing ballad, unlike the majority of the band's hits.
You can't go on thinkin' nothing's wrong
Who's gonna drive you home tonight?
I can't go on with this aching dong,
Who's gonna ride my hose tonight?
Basically, it's about a guy with blue balls who needs to score with somebody, anybody, tonight. With that premise, it's easy (and fun!) to ad-lib the rest of the lyrics.