I have so many but I can't think of any.
The first one I thought of was going to the park with my friend when we were younger, and we got lost in Wimbledon Common, very near where I used to live, and my friend kept convincing me there were Wombles and I got so excited but cried when we couldn't find them.
Another one is where this same friend and I were running and I was faster so he pushed me into stinging nettles and they went into my mouth.
Don't ask why that's a favourite..