Answer:
Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.
What is given but kept by the giver?
What is never used unless it's in a tight place?
Long and slinky like a trout, never sings till it's guts come out.
What is so fragile that saying its name breaks it?
This food is a tortilla filled with cheese and sometimes chicken before being heated or cooked.