The World According to... Boring John

A character I know quite a lot about was running in the rain last night, at the end of a six mile run. Almost back at his running club, and seemingly for no reason at all, he just shouts out the number "Five!", clear as you like. He then trailed off with "six, seven, eight"

Bit strange, really.

Wonder if it had anything to do with the hulking articulated lorry that sped close by him on the road at the time.

Was he trying to tell himself something?

Or is five just a number (another summer, sound of the funky drummer)?