Correct

满嘴跑火车

/ mǎn zuǐ pǎo huǒ chē /
Strokes
https://i.cchatty2.com/filters:format(webp)/fit-in/684x0/img/202102/满嘴跑火车-Chinese-idioms-Cchatty-bd84497f-b55a-48e5-8398-4276793017ad-1612777656.jpg

Collocation

1
满嘴跑火车的人
2
满嘴跑火车地聊天
3
总是满嘴跑火车

Definition

满嘴跑火车

Literally means:

running a train in one's mouth

Actually means:

talk big

It figuratively means what someone says is all empty, big words or brags, which are totally unreliable. Derogatory.

形容说的都是假话、大话或空话,根本不可信。具有贬义色彩。

Example

Used as predicate, attributive or adverbial adjunct. (作谓语、定语、状语)
1
Xiǎowáng
小王
zǒngshì
总是
mǎnzuǐ
满嘴
pǎo
huǒchē
火车
  
,
men
你们
yàoshi
要是
xìnwéizhēn
信以为真
de
huà
  
,
jiù
néng
可能
chīkuī
吃亏
shàngdàng
上当
  

Xiao Wang always runs the train with his mouth full, and if you believe it, you may suffer.

2
zuì
tǎoyàn
讨厌
mǎnzuǐ
满嘴
pǎo
huǒchē
火车
de
rén
  
,
zhège
这个
rén
第一
gēn
jiànmiàn
见面
jiù
zài
miànqián
面前
xiā
chuī
le
lai
起来
  
,
rán
自然
jiù
méiyǒu
没有
èr
第二
de
yuēhuì
约会
le
  

She hates people running trains with their mouths full, the first time she met her in front of her blowing up, naturally there is no second date.

3
Zài
chángchē
长途汽车
shàng
  
,
chéng
乘客
men
wèile
为了
fa
打发
shíjiān
时间
  
,
yǒude
有的
mēntóu
闷头
shuì
  
,
yǒude
有的
tīng
yīnyuè
音乐
  
,
hái
yǒuxiē
有些
rén
mǎnzuǐ
满嘴
pǎo
huǒchē
火车
tántiānshuō
谈天说地
  

On the long-distance bus, passengers in order to spend time, some sleep, some listen to music, and some people run the train full of talk.