ummmm...

I have a cold and I'm very tired...
最近我感冒了，很疲惫啊……
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Now, let's talk about "to dig out nose excrement" chat about "digging gold from our noses."
现在，让我们聊聊“挖鼻屎”这件事儿。

In fact, Actually these nose excrement boogers are our good friends.
实际上，鼻屎，是我们的好朋友。

When we feeling boring,we can to dig out nose excrement. When we are bored, we can dig them for entertainment1
当我们无聊时，我们可以挖鼻屎。

again and again... Unceaselessly we dig... keep on digging...
不停地挖，不停地挖……

It's really funny. This is really addictive!
这可真让人沉溺其中不能自拔。

Boogers are dry snot.  Snot is the wet mucous from your nose.  Digging gold from your nose is a nicer euphemism.

1.  Actually, not an accurate translation but you are repeating the same thing over and over.  This way, adds more interest to your writing.

ummmm...

I have a cold.I'm tired...
最近我感冒了，很疲惫啊……
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Now,let's talk about "to dig out nose excrement" 1) picking the nose.
现在，让我们聊聊“挖鼻屎”这件事儿。

In fact, nose excrement 2) boogers are our good friend.
实际上，鼻屎，是我们的好朋友。

When we feeling 3) bored boring,we can to dig out our boogers nose excrement.
当我们无聊时，我们可以挖鼻屎。

again and again...
不停地挖，不停地挖……

It's really funny.
这可真让人沉溺其中不能自拔。

1) 挖鼻孔是picking the nose.  "dig out nose excrement" 好像在形容某種考古實驗！

2) nose excrement這種說法很奇怪； 聽起來像耳鼻科的專用詞。 比較俗一點，但是我們會說 boogers.

3) when we feel boring - 當我們覺得我們(自己)很乏味的時候， literally!  你的意思是說，when we feel bored (我們覺得無聊的時候）