I was (and still am) a very fussy eater, but I guess my mum & dad thought I'd grow out of it or something as they still kept trying to feed me stuff they knew I didn't like and wouldn't eat.
My aversion to the undesirable food manifest in a few different ways:
Sometimes I would just sit and refuse to eat - I'd be told I'm not getting dessert if I didn't finish (that threat didn't work, my desire for dessert was lower than my dislike for the main course) or that I couldn't leave the table until I finished (apparently I was a patient child, I'd sit there pretty much indefinitely until they caved).
Other times I'd try to force myself to eat whatever it was, my gag reflex would trigger, and I'd throw up saliva and half eaten food on the plate (I can't remember if I did that deliberately to ruin the meal so they couldn't make me eat the rest of it, or if it was a genuinely involuntary reflex).
And when I thought I could get away with it I'd stow pieces of the offending food in my pockets when nobody was looking and then dispose of them in a variety of places; usually this was just throwing them out the upstairs window (my parents always wondered why the sea gulls were so fond of our garage roof), but I can remember choosing some more inventive hiding places like in the soil of potted plants and the like.
Apparently my parents never realised I was hiding the unwanted food, until over a decade later when we were moving house and on shifting the very large cabinet in our dining room they found all these shriveled black things behind it. I had to explain that they were years old pieces of french toast, sausage, beef burgers, and so on that I'd thrown back there as a child.