Yep, several times

.

Never have i ever walked in 30+ Celsius heat

I have, not my favorite haha. Also have ridden in high temperatures.

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Never have I ever accidentally gelded a stallion I didn't mean to.

I have

Never have I ever ate oranges all day.

I have!

Never have I ever (don't know if this is gonna be reposted on accident but:) broken a promise!

I haven't( I keep my loyalties)

never have I ever eaten 10 kiwi fruits without vomiting (very disturbing)

I haven't eaten kiwi ever

Never have I ever thought about climbing a tree.

I have, I have also fallen out of many trees xD

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Never have I ever eaten pizza with fish on it

Never and the thought turns me off food xD Seafood like Prawns though that's a heck yes, I have and will eat prawns on pizza a million times over!

.

Never Have I Ever witnessed a birth

I Haven't

Never have I ever written a book that isn't stupid.

I have and haven't

Never have I ever broken a bone (if this is reposted, please PM me on that!)