Evocative Vocative

Sign above a bathroom at a Tipperary Hill cafe:

CUSTOMERS ONLY PLEASE

Without the vocative comma after the word "only," we can surmise that customers only please if they are in the mood, or if someone or something suits their fancy. Or we can conclude that said customers only please, but nothing else.

And why the pleasing in the private confines of the bathroom? What the heck is going on in there? I won't ask, if you won't tell.

(Of course, switching the position of "only" invites other questions.)

All the difference one comma can make.

Chief Commando, Serial Comma Brigade