in / for donkey’s years
/fə ˈdɒŋ.kiz ˌjɪəz/idiom
for a very long time
целую вечность, сто лет
Русский аналог: «сто лет не виделись»
Обычно с Present Perfect: I’ve known her for donkey’s years.
“I haven’t seen him in donkey’s years.”
“They’ve lived there for donkey’s years.”
“We’ve been friends for donkey’s years.”