Dan’s Online Diary 

# 12.12.03 by Dan
'punter' is a stupidly-used word.
A punt is the indentation in the bottom of a wine bottle.
A punt is also a small flat-bottomed boat - so a punter is the person on the punt doing the punting.
Oh, yeah, and a punter is also 'one who gambles'.
So the term 'random punter' could have all sorts of assorted meanings, none of which actually mean what 'random punter' is intended to mean in its most common use.

Typepad
...looks so good it's tempting to actually fork out some dosh for it.