THATABOY

(slang) an exclamation of encouragement or admiration. (A corruption of "that's the boy," this expression is also seen as "that's a boy" and "attaboy.") —SHSBC Binder 22 Approved Glossary

a variation of the expression that's the boy. (slang) an exclamation of encouragement or admiration. (A corruption of "that's the boy," this expression is also seen as "that's a boy" and "attaboy.")