Meaning working in the yard or garden. Comes from the fact that farmers when working in their fields used to wear straw hats.
I was wearing the straw hat this weekend. (working on the yard)
Girl with large breasts popping out of her shirt, shirt usually being tight.
She must be smuggling piglets!
Trimming of the pubic hair, usually done around the crouch area, but can be chest hair.
This weekend my girlfriend is going to mow the yard. Or, that dude mows the yard to show his six-pack.