My biggest one was: I was water tubing with my friend(battle tubing)then a pontoon crossed our path, when my tube hit its wake it launched us both into the air, he came down on top of me and it knocked the air out of me.Trust me, it was worse than it sounds.

When I was six, I fell down a story of stairs, and almost landed on my neck nearly breaking it. The only thing that saved me was my brother.

(I landed on him instead of the hardwood stairs)

Knife fight. I've (almost) killed someone, the fucking coward was comming whit a Big Fucking FROM HELL Knife. I've almost died that day.
He came and he tried a lot of times to cut me whit the knife , i was thinking "Fuck, im dead" after successful hits of his part , I disarmed him, and i've started to cut him and punch him whit all of my fucking fury , for his luck, i didn't killed him because my Friend. Luciana pulled the knife out of my hands , i was blind of rage that day,That was a bomb of Adrenaline. I was 10. he was 15 , now i am 14. i have some scarfs on my body , and pherhaps him too.That was a really a big bomb of adrenaline.
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Detail : He tried to blind my right eye. Whit the Knife.

My biggest adrenaline rush was reading this heart stopping masterpiece of a post.

I second this, I applaud that guy for having all of those scarfs freely shown.

I think my biggest adrenaline rush was back in 2006 when a huge criminal organization here in Brazil called PCC (acronym to "First Capital's Command") was deliberately attacking police posts and cars. It was the early beginning of these attacks so people hadn't the right dimension of the problem.

So there I was on a thursday coming back from school, never had lots of friends so yes, I was walking down the street (already a bit far from school) alone when I heard some pops from somewhere near and in front of me, I thought 'damn, gotta change path', then I did it to the left in a well-known street in the neighborhood and walked ahead to turn left again, then I saw it, 4 guys, each one handing a gun bursting the hell of two cops already in the floor, dead I guess.

My legs froze, my heart started to beat like hell (i got a heart condition, have to take daily medicine, but back then I wasn't diagnosed yet). Then I turned back to where I was coming from and started to run, I heard some kind of scream or order coming from the group, something like "go go", didn't know if they were after me, but wouldn't take this chance any higher, and then I started to take quick turns.

That wasn't a violent neighborhood, i mean at all, the last crime that i remembered happening there was a guy that took a whiskey out of a bar and didn't payed lol.

Then I got tired, wasn't hearing pops anymore, the problem was that I got really off the way and didn't know for sure which way should I get. I was 13, didn't have a cellphone or a fucking penny to call home, then I heard some cars burning tires in the next street, 'fuck, again?', so I looked for somewhere I could hide, pops coming again and then an old man opened his garage gate and said "Here kid, fast", i stayed there for about 1 hour, called my mother, said what was happening and she came there to take me home (no cars, we were out there walking).

The next day news went crazy to what happened, stores went lock closed, schools too, even gas stations had they vacations a little early. It was about two weeks like this.

If you image google "PCC 2006" you will have a bit of what happened there.

my Biggest adrenaline was when I was about 10 years old.
I was with my brother and his friend walking the neighbourhood playing a game where u ring the bells of peoples houses and running away. this activity was great fun.
but wasn't that great when we were heading home, looking in the distance was 4 figures. (not in ghosts), it was late and we started to think maybe these 4 fellows could cause harm to us, so we turned back from where we just came from. and then we looked back and they were running for us. we started running too, we turned up a street to the right. we stood at the top and looked where they were, well they were coming after us, we did see a knife in the one mans hand and then it hit us, these guys weren't butchers they were criminals.
so we ran and we parkoured over some familys wall running up to there house we looked back and they were peeping over the wall hiding in the bushes.
so we stayed by that house for a while until the man of that house walked us back.
and that's it!

I got hit by a car and kinda fell onto the windshield and smashed it.
Luckily my sister was there to dial 999. ikr, England.
Does that count? :3

This was actually a recent event.

A month ago, two kids were trying to jump me at this shitty charter school I was going to; so, I punched the first one in the ribs after he tried to throw a punch at my ribs and the second kid came out like a boxer, so I hit him with a cross counter 3 times while moving back and did a spinning hook kick on him. After a few more minutes, he hits me in the head with his forearm and I got stunned, so I went to the ground and waited in a guard position, but the dude was now bleeding from his left eye and it was swollen to fuck, so he and his buddy backed off.

I found out later that they both had to go to the hospital and they're trying to sue me for assault now.

My biggest adrenaline rush was probably when I took a punch to the face for the first time. Kinda gave me enough energy to win the fight.