Let the cool flow right trough

After changing the oil I planned on changing my coolant as well.

Last time I just filled it up with tap water which itself isn’t ideal and also it changed the mixing ratio between water and the Glysantin G48 which I’m using.

Today I went to buy 3L of coolant and 5l of destilled water, prepared everything, placed a bucket below the corresponing screw and tried to open it.
Before I could think “well, that screw isn’t really tight”.. well, there it is:

I was so perplex that I took a vertical photo..

Not sure how to get the rest of it out – maybe I’ll actually have to bring it to the shop for this.
At least it’s not leaking or anything. Could’ve gotten worse.