Sometimes failing a roll leads to disastrous consequences. Rarely, failing a roll leads to something truly grand happening, either in combat or in a narrative.

Tell a story about a time a failed roll helped your team to come out ahead.

This is from an Edge of the Empire campaign, which is part of the new Star Wars RPG system. For those who haven't played it, you roll for two things: success and Advantage. Essentially if you succeed and how fortunate you are in doing it.

So, our second session in, we are responding to a distress call and our navigator is handed an easy check, one he overwhelmingly should have passed. But instead, he rolls all advantage, which means that he fails in taking us where we wanted to go.

Instead, we pop out behind a bunch of Rebellion Y-wings that were preparing for a strafing run of our proposed Lansing site. It seems that the distress call was for a downed Imperial general and his retunue.

We manage to make a deal with the Rebels to wrap up the Imperials for them, and then make a deal with the Empire officers for their rescue. We manage to steal and decode the general's classified data set, which led us to us pirating a much more valuable ship full of valuble cargo which fuels our campaign.

This sorta fits... I occasionally play D&D 2e with my dad's side of the family, and he introduced a variant rule where rolling a 1 resulted in a critical fumble of some sort, but who it affected was determined by another dice roll.

During the most recent session, my character (LG Fighter 4) got challenged to an impromptu joust with a better-equipped and higher level (Fighter 6) BBEG's champion. He's a lance Specialist on a warhorse, I'm a sword and board Specialist on a riding horse, equipped with a light lance he's only Familiar with, not Proficient. Things could have gone really badly, but as luck would have it, I rolled a 1 to hit, and the variant rules rolled that it affected him instead: he caught my lance wrong on his shield and got dismounted to the stone bridge for minimal damage.

To be honorable, as well as keep both our innocent horses out of harm's way, I voluntarily dismounted. Followed by this nobody bumpkin embarrassingly thrashing the champion in my preferred form of combat, an on-foot sword fight. Granted, I took a couple heavy crossbow bolts (the nastier versions from Player's Option: Combat and Tactics) from his treacherous lackeys for my trouble after dropping the champion (dropping me to Death's Door too), but my party dealt with them. Things could have been way more dire if I hadn't rolled that botch and taken the champion out of his comfort zone.

not my story, but I once heard of a guy playing a barbarian. A monster had grappled the party wizard, and he was trying to free him, but kept botching the attack roll and hit the wizard.

So he decided to attack the wizard next. The rest of the group was trying to talk him out of it, but nothing.

Roll. Botch. Hit the monster, max damage. GG

Well, if you're being mindcontrolled and you have to roll attack and damage against party members, you're always happy with a butchered roll.
Except with the critical failure I rolled, which normally meant you hit yourself (which was not much better then hitting my teammates, especially since I had low health because of a failed attempt to knock me out of the mindcontrol). I used a bow and arrow in a modern day zombie apocalypse setting, and the GM just loved to let the arrow bounce off things in the most crazy ways possible.
With a wide grin he rolled to see which of my own body parts I would hit --- and then just stared at the dice and simply said "That has to be the most lucky thing I've ever seen"
Turns out that I hit the walky talky that mindcontroled me (long story).
And so, 1 failed shot ruled the start of a series of very lucky rolls we really, really needed at that moment.

Happy Canada day everybody!!!

Happy Canada Day! ^_^

Not completely sure and no time to look it up, but for sure a house rule that has served those I have gamed with well is that critical successes and failures are that irregardless of the specifics. This avoids awkward "I botched but by applying the letter and not the spirit of the law I'll make it act like a crit!" or of course the inverse. ;)

Barring of course incidents where it would be even less believable for it not to work out. ;)

fighting inside a mine, ranger tries to shoot a orc with his new steel tipped arrows.
misses, hits wall of cave.
sparks.
right onto the single box of explosives the orcs brought to raid the town.

DM laghing again.

Pew

Wackiest fail?

that would be the time we tried to have the group Pack Rat disarm the giant bomb.

He had a 'distracted by the shiny thing'
flaw.

it went along the lines of..
'must disarm bomb. must disarm bomb.
ooh look flashing lights.
no- must disarm.. shiiiny!'
BOOM.

Wackiest fail?

that would be the time we tried to have the group Pack Rat disarm the giant bomb.

He had a 'distracted by the shiny thing'
flaw.

it went along the lines of..
'must disarm bomb. must disarm bomb.
ooh look flashing lights.
no- must disarm.. shiiiny!'
BOOM.

Wackiest fail?

that would be the time we tried to have the group Pack Rat disarm the giant bomb.

He had a 'distracted by the shiny thing'
flaw.

it went along the lines of..
'must disarm bomb. must disarm bomb.
ooh look flashing lights.
no- must disarm.. shiiiny!'
BOOM.

Wackiest fail?

that would be the time we tried to have the group Pack Rat disarm the giant bomb.

He had a 'distracted by the shiny thing'
flaw.

it went along the lines of..
'must disarm bomb. must disarm bomb.
ooh look flashing lights.
no- must disarm.. shiiiny!'
BOOM.

Wackiest fail?

that would be the time we tried to have the group Pack Rat disarm the giant bomb.

He had a 'distracted by the shiny thing'
flaw.

it went along the lines of..
'must disarm bomb. must disarm bomb.
ooh look flashing lights.
no- must disarm.. shiiiny!'
BOOM.

Wackiest fail?

that would be the time we tried to have the group Pack Rat disarm the giant bomb.

He had a 'distracted by the shiny thing'
flaw.

it went along the lines of..
'must disarm bomb. must disarm bomb.
ooh look flashing lights.
no- must disarm.. shiiiny!'
BOOM.