From the Dutch phrase "Voort seg ik!" literally meaning "Forward say I!". It was then adapted by South Africans into voetsek, and then eventually "footsack" in English.
It was originally meant for dogs, but is now fairly commonly used against people as well, although in this context it's meant as a light-hearted "fuck off!"
The most common variation is the abbreviated "tsack", or the colloquial "tsek".
Upon accidentally dropping a small fradgile item such as a cell phone, Ipod, camera, etc.. a last ditch effort is made to soften the obejects impact by trying to "catch" the item with your foot, much like a stall in hacky-sack. Most of the time this will not prevent the item from hitting the ground, but it will greatly lessen the impact compared to a direct drop on a hard surface, thus saving the fradgile item from severe damage such as a cracked screen, broken hinge etc..
A personwho is lucky enough to devote his life to worshiping his mistress' feet. He lives only to serve her feet.
Gemma had loved having her own footslave, she teased him, she whipped him for not licking her toes properly and she tortured him. But he loved being under her sweaty feet all day as he had a foot fetish.