Crazy or crazy in the head. Derived from half French half Vietnamese. Boocoo (Beaucoup) Dien cai dau (Crazy, or literally “crazy head”).
A phrase used by Vietnamese street vendors to American GI’s to suggest that GI’s bargaining offer is crazy. Before Americans stepped onto Vietnamese soil the French were there for around 150 years so their influence can be seen.
No need to say thank you. . .