A lesbian couple consisting of a larger, beefier woman labelled as the "hammer". She will be partnered by a more petit, slimmer women labelled as the iron.
Hammer, because she looks like she would be the one to do the DIY around the house. She could also probably pack a punch. Stereotyped by their short (or shaven) hair, butchness and work boots.
Iron, because she will be the one who does the housework (e.g. the ironing), whilst the hammer retiles the roof. She will probably be the more attractive woman in the relationship.
Anon 1: Went round to Sandra and Joans house yesterday. I tell you what Sandra's definately the hammer and Joan the iron, in that relationship.
Anon 2: How could you tell?
Anon 1: Sandra was wearing dungarees and Dr Martens fitting in an extention at the back of the house, whilst Joan washed the dishes.
Anon 2: Stereotypical Hammer and Iron relationship that.