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".
The feedback one gets from people who tried food prepared by them. Can be both positive and negative. Or simply confusing. Depends greatly on the feedback-giving person. And, of course, on the dish.
April: I love your chocolate cake. Especially the frosting... and the cute, little sugary flowers you put on top...
Maya: Well, thank you for your foodback.