Southern Spain is also famous for sayings like these, some that come to my mind that I've heard from some friends:
"Hungrier than a snail on a glass"
"Has less fat than a goat's knee"
"More leg than a box of shrimps"
"This is harder than sweeping the floor upstairs"
Why would a snail be more hungry on a glass surface than any other surface? Or for that matter, why is it hard to sweep the upper stories of the building than the ground floor?