Short for "lawn martyr". The lawtyr insists on doing the yard maintenance himself (mowing, landscaping, etc.) all the while complaining to everyone within earshot about having to do it -- and acting rather put upon.
The lawtyr is the natural foe of the housewife.
Neighbor: What's the hubby up to today?
Wife: Ah, nothing much. He's just lawtyring around the house today.