What have been your biggest fuck ups on the job?

Need to make myself feel better by sharing in some misery. Printed a shit ton of pages today in full color that were supposed to be in black and white. The work is still getting shipped to the client, but the guy is a real dick and he's getting a bunch of color pages for the cost of black and white pages (about a $150 difference.) My boss was the one who caught the mistake and had a "not mad, just disappointed" attitude about it. I have no one to blame but myself, "1-Color Black and White" was written in nice big letters on the job folder that I looked at repeatedly. I also forgot to set up the print job to include slip sheets for about 2/3's of the job, so I'm going to have to count out hundreds of sheets to add the slip sheets in by hand, because I'm not going to make the poor finisher do all that himself.

Not the worst mistakes in the world but I'm beating myself up over it because I'm only on my third week at this place and have already screwed several things up. So please help me feel like I'm not alone and share what stupid fuck-ups you've made.

Edit: Thought of a funnier one that happened last week. Our shop is right next to the local High School, so we got the idea to put out a big sign to congratulate the graduating seniors. We get it all designed and printed on the wide format printer and have it ready to go out front. Then one of our screenprinters looks at it and points out that it's spelled "Congratulations" not "Congradulations". No less than 5 people had looked at this sign, including the owner. It took until person number 6 to catch it. All we could do was just laugh about it and make a new sign.​