Будуняки is a colloquial and somewhat humorous term for a hangover, specifically a severe one. It's not a standard dictionary word, which makes it interesting and unique to this song's informal tone.
In the lyrics, it appears in the line "На ранок з будуняки голова тріщить" (In the morning, from the hangover, the head is splitting), perfectly capturing the intense discomfort after a night of heavy drinking. Its informal nature adds a touch of authentic, everyday Ukrainian slang.
"По 50" is a cheerful, tongue-in-cheek anthem about drinking culture in Ukraine. The title refers to "50 grams", the classic way friends order a round of spirits together.
The song follows a group of guys unwinding after a busy week: one bottle finishes, another gets chased down, the local shop is closed, so they head to the village lady who always has a bottle on hand. The chorus jokes that skipping a drink makes you the odd one out at a party, exaggerating the pressure to join in.
Later verses cover the classic hangover cure (pickle brine, then a shot of vodka, "like cures like") and a warning to still behave yourself. It's a light, party-song wink at drinking traditions rather than a serious statement, and it includes some crude language along the way.