screw up

You can use it as a verb to describe your own actions. You can also use it to describe someone else's error. It is a phrasal verb, so it is quite flexible. You can say I screwed up the interview or I screwed the interview up. Both are perfectly fine. You can even use it as a noun: That was a big screw-up. Just remember it is an active phrase. It shows that an error happened because of someone's actions.

Use this when you are talking to friends or coworkers you know well. It is great for admitting you forgot to buy milk. It works well when you accidentally sent an email to the wrong person. It sounds honest and relatable. In a meeting, you might use it to take responsibility for a small project delay. It shows you are human and can admit when you are wrong.

Avoid this in very formal writing or with high-ranking bosses you don't know. Do not use it in a legal document or a formal apology to a stranger. It is a bit too casual for those moments. Also, be careful with the phrase screw you. That is an insult and is very different from screw up. Don't mix them up! You might also avoid it in extreme tragedies. If a building falls down, screw up sounds too light and insensitive.

This phrase likely comes from the world of mechanics and engineering. If you over-tighten a screw, you might strip the threads and ruin the hole. Once that happens, the screw won't stay in place. The whole project is suddenly broken. In American culture, admitting you screwed up is often seen as a sign of character. People usually prefer an honest I screwed up over a long, fake excuse.

You will often hear mess up as a softer alternative. If you want to be more vulgar, some people use f*** up, but stay away from that in professional settings! You might also hear foul up, which is a bit old-fashioned. If someone is constantly making mistakes, you might call them a screw-up. It is a bit mean, so use that one carefully with friends only.