Correct

没头没脑

/ méi tóu méi nǎo / 
Strokes

Example

Definition

illogical; without rhyme or reason

1
Méitóuméinǎo
没头没脑
de
的
huà
话

pointless remark

Definition

(do or say sth) abruptly; all of a sudden

2
Lǎoshī
老师
yī
一
zǒujìn
走进
jiàoshì
教室
jiù
就
bǎ
把
yuēhàn
约翰
méitóuméinǎo
没头没脑
dì
地
xùnchì
训斥
le
了
yī
一
dùn
顿
  
。

No sooner had the teacher entered the classroom than he gave John a good dressing down.

Definition

(do sth) regardless of consequences

3
Méitóuméinǎo
没头没脑
dì
地
dá
打
rén
人

beat sb relentlessly/mercilessly