This is a little concept that everyone should live by. It's figurative in a way since I don't suggest actually hitting someone.
Never trust anyone who is too far away for you to hit.
If you actually think about this it all makes sense. This is why long distance relationships hardly ever work. I've had experience with people who've I've been far away from and ended up getting screwed over.
I went to camp this summer and asked my friend to do me a favor and work on this project of ours. He said OK but there was no way for me to force him to do it since I was far away and wouldn't see him for three weeks. It never got done because when I got home and was close enough to hit him he went on vacation and that was the end of that.
My brother was in a relationship for two or three years in college and then he went and joined the Peace Corps for two years. Soon after he got back his girlfriend broke up with him and went off to be with her ex-boyfriend who had become her "friend" while he was gone.
I can think of other examples of this saying coming into play but i know some of the people might read this and get pissed so i won't bother.