Your most nerve wrecking / riskiest deployment?

I once made a deployment during a meeting of my boss and the client, while they were using said a live chatting feature, in order to fix a bug in said chat.

This was essentially also testing rolling deployments and and state handoff at the same time.

My boss and the client didn't notice the deployment (My boss was in on it btw).
Epic win

It was my first deployment ever. I was taking over the entire development dept at the same time (the lead, and only other dev, had just resigned).

I was deploying about 6 months of changes at one time because there was no way to split it up.

If I remember it was about 10 major features and about 20 minors. Around 5 database migrations that touched about every table in some way.

The deployment took just over two hours and I was a fucking wreck.

I got through it though, and every single deployment or migration since has been easy as Sunday morning.

I just make two deployment environments now

stable one for show off to boss.
And dev one for all the rest.

I pushed a change right before launch, bypassing the testing and going right to production.

I ended up breaking everything, so I'm a lot more cautious about doing this now