The word came from French long ago and now sounds natural, friendly and casual — not affected at all. "Благодаря"
is the neutral "thank you" for every situation: with officials, older people, in emails. You can also say "Мерси много!"
(thanks a lot). The usual replies are "Моля"
(you're welcome — the same word as "please") and "Няма защо"
(don't mention it).
Explore Bulgaria
Merci and thank you
Bulgarians say "мерси"
all the time.

History of Bulgaria
An illustrated history of Bulgaria
Explore Bulgaria

Ayde — come on!
"Айде"
(or "хайде"
) is one of the most useful words in Bulgarian.

Sharon Hahn Darlin · CC BY 2.0 · Source
Ayran
"Айрян"
is a cold drink made of yoghurt, water and a pinch of salt.

Shake for yes?
Traditionally, Bulgarians shake their head from side to side to mean "да"
(yes) and nod to mean "не"
(no).