Attaboy
来自Big Physics
Safin（讨论 | 贡献）2022年4月28日 (四) 18:55的版本 （建立内容为“Category:etymology == google == [https://www.google.com.hk/search?q=attaboy+etymology&newwindow=1&hl=en ref] early 20th century: probably representing a casu…”的新页面）
early 20th century: probably representing a casual pronunciation of that's the boy .
wiktionary
Variant pronunciation of "That's the boy!", a cry of encouragement, especially to children and pet dogs.
etymonline
attaboy (interj.)
1909, originally in baseball slang, said to be from common pronunciation of "that's the boy!" a cheer of encouragement or approval. I'm the boy for ______ "I'm willing and capable at" is attested from 1843. Related: Attagirl (1924).
