The carboy's bung was blown off by the pressure and a lot of the must escaped.
It is almost as if I didn't add anything last night because the must is exactly at the 19L (5 Gallon) mark again. Check it out
On this picture you can also see my hydrometer (I'm pretty sure it is a a hydrometer) in a sample of the must. I tasted the must afterwards and it tasted terrible, kind of like cough syrup. The smell wasn't any good either. It smelled like ACETONE!... I guess it's normal though. I bet the acetone smell is mostly due to the oranges and that the cough syrup taste is normal for a work in progress. I wasn't expecting anything nice but hell was I surprised!
I decided on a course of action
I used the hydrometer to make a sample honeywater mix with the same reading as the must and scaled it up to find out how much honey I needed to make it a six gallon batch again. According to my calculations 1224 g Honey (2.7 lb) was the right amount so I bought some honey, dissolved it in water and added it to the must. I also added 15 raisins because that's how many raisins I found outside the carboy
Here it is after the procedure
I left the three inches this time for foaming (or something) but I am planning to add water after a few days if this works out as intended
Live and learn, eh? :)
... again, I hope this works as intended!