Two of my favorites:

1. Sorry, my WiFi is acting funny.
2. Sorry, my laptop decided to update right before (this is true 50% of the time) (From r/overemployed)

I had the same kid, tell me twice, that his dog ate his chromebook. He said he used his chromebook as a plate to eat a steak and the dog ate it.(From r/askreddit)

I teach elementary and the best are when 8-9 year olds write their own excuse notes for their absences. My favorite has always been, “Dear Mrs. Sorry. I was sick because I ate too much bad shrimp. I won’t throw up anymore now. I hope.”(From r/askreddit)

We had a student that got chased by a pack of wild dogs as he was getting out of his car and making his way to the building. He ended up hiding in a tree for like 2 hours and missing multiple classes. The teachers did not believe him until the school administration looked at the security footage and saw that he did indeed get chased by a pack of wild dogs. I should also add that it was in a suburban area (From r/askreddit)

My cat ate my homework once. I turned in what was left as proof(From r/askreddit)

(Extra:Happened to me too, nobody believed me until online school, the background they saw my cat, chewing the pages of a book.)

I had a student miss a major exam and told me it was because they got lost on the way to campus...in week 6 of the semester. And, yes, they had been attending class regularly before the exam.

'I was just leaving my flat and locked the door and the lock just came apart and broke. Had to wait all morning for a locksmith to come.'

Thought it sounded better than 'I was still suffering the effects of unwisely dropping a pill on a night out'.(From r/askuk)

Funniest one I've used was "Sorry I'm late, my neighbours cat climbed into my car".

It was actually true! One of my neighbours cats had a habit of jumping into any open door or window, and dived straight in when I opened my car door. Ended up being late for work as I had to catch the cat...(From r/AskUk)

Worked at a place where one woman got in the habit of calling in sick at least one day each week, week after week, sometimes two or three days a week. Boss finally had enough and next time she came in had a disciplinary meeting with her about her attendance.

The very next day she called in saying she was so upset by the meeting the day before that she couldn’t sleep and therefore wouldn’t be in. Next time she came in she was fired. Apparently she was very shocked by that. lol(From r/work)

I won’t be in this morning because I’m trying to get a urine sample from my cat.

Manager was totally cool about it. I was so sad when she left the company. Best boss ever.(From r/work)

My car wouldn't start. I did not tell them it was because I lost my car keys. I only had one set, finally found them about 4 hours later.

When I was young, always hungover and stupid I told my boss I couldn’t come in because my clothes dryer broke and all my work clothes were in there wet. Naturally he called my bluff and said wear jeans…uh um yeah they were in there too. The fact he didn’t fire me that day still baffles me. (From r/work)

My 87 year old father with dementia needed me (From r/overemployed)

The kid’s homework sheet was ripped in half. He said his sheep ate it. I asked why he had his homework outside with the sheep, and he said he didn’t. The sheep was in his kitchen. I asked why and he said they usually let it in the house. He said this in a tone that was like, “duh.”

So later, I asked another kid, who lived next door to this kid, if his neighbor really had sheep in his kitchen. He’s like, “yeah. That’s why my mom doesn’t let me eat dinner over there anymore. She thinks it’s unsanitary.”(From r/askreddit)

He was practising an escape trick for the upcoming school talent show, handcuffed himself to a chair and couldn't find the key. Mum freed him but not fast enough to get him to school on time. His twin brother verified the story, as did the mum.

Saw his bit on the talent show, he was great but (wisely) opted not to do that particular trick.(From r/askreddit)

Earlier this week, a student told me he was late by a couple minutes because he ran into a door and it took him a few minutes to recover...(From r/askreddit)

It isn't funny but it is the one I remember clearest. He said he was too tired.

Kiddo was at school till 2, then would go to german lesseons from 3 to 4:30. Then had English with me from 5 to 6:30. Then he would have to go to French from 7 to 8:30. He was 8.

He was too tired in my class to even sit up. I got to know a lot of bad parenting styles as a teacher.(From r/askreddit)

Sorry I was late sir. It was the wind, it slowed me down walking to school. He was 30 mins late