In computing, what is foo, sneaker and time bomb?

Answer 1

foo is used in tutorial type things as name that can be anything, to signify that it can be anything, for instance

int foo;

shows the syntax of how to declare an integer, something like

int integer;

is confusing, it looks like it might be an integer, named int (when you're trying to show someone the syntax for making a declaration they have no idea which one will be the name), whenever you see foo, you know that it is just a name of something and could be replaced with anything

a sneaker you wear on ur foot, time bombs blow stuff up