A Venn Diagram is a pictorial representation of shared and unshared relationships between sets.  It comprises overlapping circles, typically three.

An example might show tall men, ginger-haired men and left-handed men.  Some men would be tall but neither ginger nor left-handed (A in diagram 2); some men would be tall and ginger but not left-handed (AB); and some tall and left-handed but not ginger (AC).  A tiny proportion, represented in the centre of the Venn (ABC), would be all three.

Now I think I have stumbled upon a relationship involving men who drive those Hummer-type vehicles, men who own aggressive dogs and men with tattoos.

The Hummer-type vehicles are those black, hostile-looking off-roaders with an extra conservatory built on the back.  They all have names like AN(I)MAL, BARBARIAN and WARRIOR.

What gets out of them invariably matches the description – Shaved-Head Man with an extensive array of body art.  Now I’m not against tattoos.  I know many men who’ve got them; but nobody nice.

He also owns a dog or two; not, as you will have guessed, a Pekinese or a Collie, but something which compliments more suitably the persona – Bull Terriers or Rottweilers, which would be straining at the leash if they were on one.

So I reckon that a census of these three sets would show in the Venn Diagram a centre-piece which was extraordinarily large.  Put another way, if you fit any one of the sets, look sharp; you’re missing out on the other two.