Not funny at the time but when my son was born he wasn't breathing and the midwife grabbed him and shouted "we've got a flat baby" while running out the room with him. My wife high on all the drugs they'd given her turned and looked at me all confused and asked "we've got a black baby". To save her panicking I just said yes. Scary at the time but funny now.
Years ago my wife and I used to keep chickens and had a veg patch, the veg patch was surrounded by a 2 foot wall and the chickens coop was next to it. After finding rat holes I asked my brother to help me move the coop, he turned up all dressed up in brand new gear as he was going out on the lash.
Watching him place every step carefully to avoid getting any mess on his shoes. The coop was moved I poured half a gallon of petrol down one of the holes (I'd been told this was the most effective way to get rid of rats), I lit a match and threw it down, the whoosh and flame that came out the hole was at least 10 feet high.
Amused by what I'd seen I asked my brother to fill a hole further down the veg patch as I was going to get my phone to film it. As I come back into the garden I hear a whoosh and see a flame go up my brother, he threw the petrol can and dived face first into the veg patch covering himself and all his new clothes in mud head to toe. I was pissing myself so hard I couldn't ask if he was ok for ages, luckily no injuries apart from a few singed hairs, I can't tell the story without crying with laughter.