Kalsarikännit in Finnish. Literally "underwear drunk" , or more spesifically, "long john drunk".
Meaning deliberately getting drunk alone at home in your underpants with zero plans of meeting anyone or going out. I think other nations do this as well, but don't have a word for it.
Delightfully relaxing and therapeutic at times, slightly concerning if done exessively.
At best a wonderful opportunity to touch base with your self, your life and your deepest thoughts and feelings. And/or watch that one cheesy comedy from 1992 you love but can't get any of your friends to watch with you because they have standards.
At worst you wake up to an unholy mess accompanied by a killer headache, cheese all over the bed, cryptic messages on ripped up pieces of pizza box cardboard written by you to you all over the kitchen, and have nobody to blame than yourself.
I've seen it translated somewhere as "pants drunk", but actual pants are much too fancy attire for this. For full experience you need to wear your most comfortable, decades old long johns that have holes and a weird stain that somehow never comes off in the wash.