I just did mine! I had resupply equipped and expecting to throw a frag up a ramp into someones face. But I didn’t check and I only had a pulse grenade. My shield was down, I tossed it right in front of me to get it to bounce just right and… bam!
Before I new it I had incinerated myself and the guy that last shot me got a free kill.
XD
Ruined a spree and everything.
Big Team on Exile…enemy Warthog is barreling towards me. I jump and throw a perfect sticky, blowing up the 'hog and earning a double kill. A second later, I hear,“Betrayal!”. A buddy I was partied up with had just respawned and a chunk of the Warthog hit and killed him. He just started laughing. Glad it was him and not a random or they probably would have booted me.
I had rockets and some red was trying to splatter me with a ghost! I jumped over him, and while in flight, launched directly below. I killed myself…
:’(
Done a lot of fails in my life.
Gone to drive through exile to have my team mates plasma send me into him and betray him.
I’ve destroyed Phantoms in spartan ops for a chunk to hit me and kill me.
Been times I’ve bounced my grenade (with both grenade perks) for it to come back to me and either kill me or take my shields off leaving me open for a free kill.
Playing Cops and Robbers in customs, the one I made, and when I got out of the vehicle depot with a Wraith, I just suddenly got launched OUTSIDE the map. 0_0
Either any time ive blown myself up or the only time I got killed by my own ordinance…
Ordnance drop
Speed Boost!
I thought I was sonic the hedgehog, ran straight into a ghost at a full speed sprint for the hijack and splattered my self…
Basically everything that happens to me when I try t drive a vehicle that isn’t a Scorpion or Banshie, as well as any time I try to use heavy or explosive weapons.
I flip vehicles in while driving in straight lines. Never understood how.
I also tend to blow myself up with every explosive weapon except a railgun or Reach’s grenade launcher. Even grenades are a 50/50 risk, and my plasmas never seem to want to leave me because they always bounce (and many have been lunched by a another explosion) back and stick to me.
Check “Sticky detonator fail” in my file share and you’ll see one of my biggest fails 
1st time I played Lightning Flag I killed myself with my personal ordinance EVERY time.
I caught someone’s grenade with my face from across the map.
I called ordnance and the enemy banshee was just above me the ordnance killed the banshee but it got stuck in the middle of the sky.
Also I think this thread would fit better on the General Discussion Forum-Click Here as it is more like Halo general and not only Halo 4 
the worst fail ive ever had was buying this game.
I missed a warthog with an Incinerator Cannon…twice >_<’
It was a Lag on Settler and i managed to have Hijacked a Warthog and with that lag, sent me straight up to kingdom come, b/c someone decided to fire the Incineration Cannon.
> I called ordnance and the enemy banshee was just above me the ordnance killed the banshee but it got stuck in the middle of the sky.
>
> Also I think this thread would fit better on the General Discussion Forum-Click Here as it is more like Halo general and not only Halo 4
I didn’t know at first that this could happen, until I got killed by an ordnance drop (the grenade spawn in the middle building on Complex). That wasn’t the fail, though.
The fail was when I let it happen again. Twice, in fact.
i was on Exile and finally the people let me have the scorpion
(even if normally im not a vehicle user the 80% of the time)
then wild lag appear!!!
after lag ends, i was in the other side of the bridge and the scorpion was climbing the rock close to the man cannon
my scorpion do a barrel roll
oh but… THATS NOT ALL XD
wild lag came again
and didn’t let me get out of the scorpion and some random spartan laser shot killed me on the scorpion
i lost a frenzy /._./
> Playing Cops and Robbers in customs, the one I made, and when I got out of the vehicle depot with a Wraith, I just suddenly got launched OUTSIDE the map. 0_0
Doesn’t strike me as being your fault, those are some of the most lethal glitches though.
The rocket splash damage off the wall suicides!
I will say my biggest fails are when i am stalking, i go to start the assassination and get assassinated. So embarrassing!
I’ve had too many to count.