18 is the age in the United States where our young people are legally of age to vote. A golf game typically consists to 18 holes. Big rigs that travel the highways and byways are referred to as 18 wheelers. Hangar 18, located in Ohio, is the supposed location of an alien aircraft that landed in Roswell, New Mexico in 1947.
18 Again! was a 1988 George Burns film. If you haven’t seen it, well, you weren’t missing anything of particular cinematic relevance. But it was on cable a ton when I was a teen so consequently it is burned into my memory.