Correct

胡乱 vs 乱 vs 随便

/ húluàn vs luàn vs suíbiàn / 
Strokes

Formula

1
随随便便 (AABB)

Definition

胡乱 is an Adverb, and 乱 and 随便 are both Adjectives, which all means “at random; in disorder; in confusion; casual”.

Example

胡乱 means "careless, casual".
胡乱 in examples ① and ②, though colloquial, is rather refined as it originated from ancient vernacular.

In examples ① and ②, 随便 can also be used, which is really colloquial.
1
Tā
他
qǐ
起
wǎn
晚
le
了
  
,
húluàn
胡乱
  
(
suíbiàn
随便
  
)
cā
擦
le
了
bǎ
把
liǎn
脸
jiù
就
gǎn
赶
qù
去
shàngbān
上班
le
了

He got up too late, so he washed himself briefly and went to work.

2
Tiānhēi
天黑
dēng
灯
àn
暗
  
,
tā
他
húluàn
胡乱
  
(
suíbiàn
随便
  
)
zhǎo
找
le
了
jiàn
件
yīfu
衣服
pī
披
shàng
上
jiù
就
zǒu
走
le
了
  
。

It was dark and the light was dim, so he put on a coat casually and left.

胡乱 also means "unreasonable, willful".
In example ③ one can also say 随便批评(人).

In example ④ 胡乱 can also be replaced by 随便, but not as serious as 胡乱. One can also say 乱批评人, 胡乱骂人 with a similar meaning.
3
Tā
他
huà
话
hái
还
méi
没
tīng
听
wán
完
  
,
jiù
就
húluàn
胡乱
  
(
suíbiàn
随便
  
)
dì
地
pīpíng
批评
le
了
yī
一
tōng
通
  
。

He just heard part of it and began criticizing without reasons.

4
Nǐ
你
zěnme
怎么
húluàn
胡乱
  
(
suíbiàn
随便
  
)
mà
骂
rén
人
  
?

Why do you swear others without reasons?

乱, to mean "disorderly, confused, in a mess".
5
Zhè
这
piān
篇
wénzhāng
文章
xiě
写
de
得
tài
太
luàn
乱
  
。

The article has a disorderly organization.

6
Wūzi
屋子
lǐ
里
dōngxī
东西
duō
多
  
,
luàn
乱
de
得
hěn
很
  
。

The room was a mess for it was full of items.

乱, to mean "confused, perturbed".
7
Wǒ
我
xīnli
心里
hěn
很
luàn
乱
  
,
ràng
让
wǒ
我
ānjìng
安静
yī
一
xià
下
  
。

I'm in a mess so please let me be.

乱, to mean "to create a disturbance".
8
Zhè
这
fú
幅
huà
画
suīrán
虽然
shì
是
yànpǐn
赝品
  
,
dàn
但
zúyǐ
足以
yǐjiǎluànzhēn
以假乱真
  
。

The picture is a fake, but it can create confusion.

9
Biè
别
ràng
让
zhèxiē
这些
suǒshì
琐事
dǎluàn
打乱
wǒmen
我们
de
的
gōngzuò
工作
chéngxù
程序
  
。

Don't make the trivials disturb our routines.

乱, to mean "willful, as one pleases".
Example ⑩ can be turned into 胡乱发表意见 or 随便发表意见 or 随便乱说.

Example ⑪ can be turned into 胡乱吃东西 or 随便吃东西.

Example ⑫ can be turned into 随便跑 or 随便乱跑. 胡乱 cannot be used here.
10
Nǐ
你
bùyào
不要
bùdǒngzhuāngdǒng
不懂装懂
  
,
luàn
乱
shuō
说
yīqì
一气
  
。

You just comment unknowingly and pretend to know what you don't know.

11
Xiǎotānr  
小摊儿
shàng
上
de
的
dōngxī
东西
bù
不
wèishēng
卫生
  
,
bùyào
不要
luàn
乱
  
(
húluàn
胡乱
  
)
  
(
suíbiàn
随便
  
)
chī
吃
  
。

Don't buy the food in the stalls outside for it is dirty.

12
Nǐ
你
gāng
刚
dào
到
zhège
这个
dà
大
chéngshì
城市
  
,
hái
还
bù
不
shúxī
熟悉
  
,
biè
别
gèchǔ
各处
luàn
乱
  
(
suíbiàn
随便
  
)
pǎo
跑
  
。

Don't go everywhere, for you came to the city not long and are unfamiliar with it.

随便, to mean "no matter (how, what, where, etc.)".
13
Suíbiàn
随便
shénme
什么
diànyǐng
电影
  
,
tā
他
dōu
都
ài
爱
kàn
看
  
。

He likes a variety of films.

14
Suíbiàn
随便
zhōngcān
中餐
xīcān
西餐
dōu
都
kěyǐ
可以
  
,
wǒ
我
shì
是
kèsuízhǔbiàn
客随主便
  
。

I will take what you prefer whether it is Chinese food or Westerm food.

随便, to mean "casual, random".
15
Biè
别
kèqi
客气
  
,
suíbiàn
随便
zuò
坐
  
。

Make yourselft at home, and take your seat please.

16
Zài
在
dàhuì
大会
shàng
上
jiǎnghuà
讲话
bù
不
néng
能
tài
太
suíbiàn
随便
  
。

You cannot deliver a casual speach at a meeting.

17
Lǎopéngyou
老朋友
jiànmiàn
见面
suíbiàn
随便
xiántán
闲谈
qǐlai
起来
  
。

The old friends chatted as they met each other.

随便, to mean "arbitrary, as one pleases, careless".
In example ⑱ 胡乱放 or 乱放 can be used instead.

It is noteworthy that 随便 can be used together with 乱.
18
Píngshí
平时
dōngxī
东西
suíbiàn
随便
  
(
húluàn
胡乱
  
)
  
(
luàn
乱
  
)
fàng
放
  
,
dào
到
yòng
用
de
的
shíhou
时候
shénme
什么
dōu
都
zhǎo
找
budào
不到
  
。

You cannot find it when needed, for you put it away casually.

19
Zhèxiē
这些
cáiliào
材料
bùyào
不要
suíbiàn
随便
luàndòng
乱动
  
。

Don't touch these materials without their owner's consent.

随便 can be reduplicated into 随随便便 (AABB).
随随便便 (AABB)
20
Tā
他
zhège
这个
rén
人
zǒngshì
总是
suísuíbiànbiàn
随随便便
  
,
shénme
什么
shìqing
事情
dōu
都
bù
不
fàngzài
放在
xīnshàng
心上
  
。

He is a casual man and would not like to have a lot on his mind.

21
Zhè
这
fēng
封
xìn
信
hěn
很
zhòngyào
重要
  
,
yào
要
hǎohǎo
好好
kǎolǜ
考虑
yī
一
xià
下
zěnme
怎么
xiě
写
  
,
suísuíbiànbiàn
随随便便
kě
可
buháng
不行
  
。

It's not OK if you write the letter casually for it is very significant.